Conductive loop detection member

ABSTRACT

A fluid treatment cartridge includes a housing having a fluid inlet and a fluid outlet with a treatment media contained within the housing. The fluid treatment cartridge includes a detection member comprising at least one closed electrically conductive loop having at least two spatially separate sections. Each of the sections generates a magnetic response when at least one section is electromagnetically excited. The magnetic response of each section is predetermined by the physical shape of the section and comprises at least one of a predetermined magnetic phase response and a predetermined magnetic amplitude response. The predetermined magnetic response of at least one other section of the closed electrically conductive loop corresponds to at least a one digit code.

TECHNICAL FIELD

This disclosure relates generally to authentication of fluid treatmentcartridges and to associated device, systems, and methods.

BACKGROUND

Many systems use removable components that can be installed, removed,and/or reinstalled or replaced from time to time. Examples of suchsystems include fluid treatment systems that use treatment cartridges,air circulating systems that use filters, printing systems that use inkcartridges, vacuum systems that use filter bags, and many others.

BRIEF SUMMARY

According to some embodiments a fluid treatment cartridge includes ahousing having a fluid inlet and a fluid outlet with a treatment mediacontained within the housing. The fluid treatment cartridge includes adetection member comprising at least one closed electrically conductiveloop having at least two spatially separate sections. Each of thesections generates a magnetic response when at least one section iselectromagnetically excited. The magnetic response of each section ispredetermined by the physical shape of the section and comprises atleast one of a predetermined magnetic phase response and a predeterminedmagnetic amplitude response. The predetermined magnetic response of atleast one other section corresponds to at least a one digit code.

Some embodiments involve a system that comprises a fluid treatmentcartridge and a reader. The fluid treatment cartridge includes a housinghaving a fluid inlet and a fluid outlet with a treatment media containedwithin the housing. The fluid treatment cartridge includes a detectionmember comprising at least one closed electrically conductive loophaving at least two spatially separate sections. Each of the sectionsgenerates a magnetic response when at least one section iselectromagnetically excited. The magnetic response of each section ispredetermined by the physical shape of the section and comprises atleast one of a predetermined magnetic phase response and a predeterminedmagnetic amplitude response. The predetermined magnetic response of atleast one other section corresponds to at least a one digit code. Thereader includes at least one transmit element and at least one receiveelement. The transmit element is configured to transmit anelectromagnetic signal that electromagnetically excites the at least onesection of the closed conductive loop. The predetermined magneticresponse of the at least one other section of the closed conductive loopgenerates a signal on the at least one receive element that representsthe code.

Some embodiments are directed to a method of operating a system thatincludes fluidic treatment cartridge comprising a housing having afluidic inlet, a fluidic outlet and a treatment media disposed withinthe housing. The housing includes a closed electrically conductive loop.At least one section of the closed electrically conductive loop iselectromagnetically excited. A predetermined magnetic response isgenerated in at least another section of the closed conductive loop inresponse to electromagnetic excitement of the at least one section ofthe closed conductive loop. The predetermined magnetic responsecomprises at least one of a magnetic phase response and a magneticamplitude response. The predetermined magnetic response corresponds toat least a one digit code.

Some embodiments involve a device that includes a housing having a fluidinlet and a fluid outlet with a treatment media contained within thehousing. The device includes a detection member comprising at least oneclosed electrically conductive loop. The closed electrically conductiveloop has multiple spatially separate loop sections including at leastone excitation section and one or more response loop sections disposedrespectively in multiple spatially separate sections of a detectionarea. Each of the response loop sections generates a predeterminedmagnetic response when the excitation loop section iselectromagnetically excited. The magnetic response comprises at leastone of a predetermined magnetic phase response and a predeterminedmagnetic amplitude response. A spatial arrangement of the predeterminedmagnetic responses of the one or more response sections within themultiple detection area sections corresponds to a multi-digit code.

These and other aspects of the present application will be apparent fromthe detailed description below. In no event, however, should the abovesummaries be construed as limitations on the claimed subject matter,which subject matter is defined solely by the attached claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a conceptual diagram illustrating a treatment cartridge thatincludes a detection member in accordance with some embodiments;

FIG. 1B depicts a detection member comprising an electrically conductivematerial arranged as a continuous electrically conductive loop inaccordance with some embodiments;

FIG. 2A is a conceptual diagram that shows the cartridge of FIG. 1Afluidically, mechanically, and inductively coupled to the host device inaccordance with some embodiments;

FIG. 2B is a block diagram of a detection system in accordance with someembodiments;

FIG. 3 illustrates a replaceable cartridge inserted in a manifold of ahost device in accordance with some embodiments;

FIG. 4 shows a graph of a signal transmitted from a transmitter element,a graph of the signal on sensor element when the loop is not present,and a graph of the signal generated from the loop on sensor element 361when the loop is present in accordance with some embodiments;

FIG. 5A illustrates a component having a detection member comprising atleast one closed electrically conductive loop having at least spacedapart two loop sections in accordance with some embodiments;

FIG. 5B shows a portion of a reader system including a sensor array withfour sensor elements and a detection member comprising a closedelectrically conductive loop disposed within a detection area inaccordance with some embodiments;

FIGS. 6A and 6B show a phase shifting feature of a loop section inaccordance with some embodiments;

FIGS. 7A through 7C show a notch feature of a loop section in accordancewith some embodiments;

FIGS. 8A through 8C show a branch feature of a loop section inaccordance with some embodiments;

FIGS. 9A and 9B show a notch features of a loop section in accordancewith some embodiments;

FIG. 10 illustrates a closed conductive loop with multiple turns in someloop sections in accordance with some embodiments;

FIGS. 11 and 12 show masking features of loop sections in accordancewith some embodiments;

FIGS. 13A through 13G show closed conductive loops with crossoverfeatures in between some loop sections wherein the magnetic response ofthe loop sections corresponds to a code in accordance with someembodiments;

FIGS. 14A through 14G show closed conductive loops with notch featuresin some loop sections wherein the magnetic response of the loop sectionscorresponds to a code in accordance with some embodiments;

FIGS. 15A through 15G show closed conductive loops with some multipleturn loop sections wherein the magnetic response of the loop sectionscorresponds to a code in accordance with some embodiments;

FIGS. 16A through 16C show examples of detection members comprisingmultiple inductively coupled, galvanically isolated closed conductiveloops wherein at least one section of the closed conductive loops has adifferent magnetic phase response when compared with at least one othersection of the multiple closed conductive loops;

FIGS. 17A through 17E show examples of detection members comprisingmultiple inductively coupled, galvanically isolated closed conductiveloops wherein at least one section of the closed conductive loops has adifferent magnetic amplitude response when compared with at least oneother section of the multiple closed conductive loops;

FIGS. 18A through 18D a closed conductive loop and sensor array arrangedand rotated along the longitudinal axis (y-axis) of a treatmentcartridge in accordance with some embodiments;

FIGS. 19A through 19C illustrate a closed conductive loop and a sensorarray oriented along the circumference of a treatment cartridge inaccordance with some embodiments;

FIGS. 20A through 20D illustrate a closed conductive loop that includesa loop section that is oriented at an angle to the other loop sectionsand a sensor array that includes a corresponding sensor element orientedat an angle to the other sensor elements in accordance with someembodiments;

FIGS. 21A through 21C illustrate an embodiment in which the planarsurface of the closed conductive loop is perpendicular to the planarsurfaces of the sensor elements of the sensor array in accordance withsome embodiments;

FIGS. 22A through 22C illustrate a closed conductive loop whereinsections of the closed conductive loop are rotated along thelongitudinal axis (y-axis) of the treatment cartridge in accordance withsome embodiments;

FIGS. 23 through 26 are flow diagrams that illustrate the operation of adetection system according to some embodiments;

FIGS. 27A-27C compare graphs of the baseline and measurement signals fora simple conductive loop having the configuration generally shown inFIG. 1B and having three sections;

FIGS. 28A-28C compare graphs of the baseline and measurement signals fora conductive loop having the configuration generally shown in FIG. 9Aand having three sections where the center section has notches at eitherside of the center loop section that increase the geometrical similaritybetween the center loop section and corresponding center sensor element;

FIGS. 29A-29C compare graphs of the baseline and measurement signals fora conductive loop having the configuration generally shown in FIG. 7Aand having three sections with a notch extends across the center loopsection, reducing the geometrical similarity between the center loopsection and the corresponding center sensor element;

FIGS. 30A-30C compare graphs of the baseline and measurement signals fora conductive loop having the configuration generally shown in FIG. 8Aand having three sections with two loop branches that extend across thecenter loop section, reducing the geometrical similarity between thecenter loop section and the corresponding center sensor element.

FIGS. 31A-31C compare graphs of the baseline and measurement signals fora conductive loop having the configuration generally shown in FIG. 11and having three sections with a conductive peninsula that extendsacross the center loop section, masking the amplitude response of thecenter loop section;

FIGS. 32A-32C compare graphs of the baseline and measurement signals fora conductive loop having the configuration generally shown in FIG. 12and having three sections with a conductive island that extends acrossthe center loop section, masking the amplitude response of the centerloop section;

FIGS. 33A-33C compare graphs of the baseline and measurement signals fora conductive loop having the configuration generally shown in FIG. 6Aand having three sections with cross over between the rightmost andcenter loop sections;

FIGS. 34A-34C compare graphs of the baseline and measurement signals fora conductive loop having the configuration generally shown in FIG. 6Aand having three sections with a first cross over between the rightmostloop section and the center loop section and a second cross over betweenthe center loop section and the leftmost loop section;

FIG. 35A is a block diagram illustrating a reader/capacity sensor inaccordance with some embodiments;

FIG. 35B is a block diagram illustrating a reader/capacity sensor wherethe sensor elements shared between capacity sensing and reading the codeof the closed conductive loop in accordance with some embodiments;

FIGS. 36A and 36B are a diagrams illustrating in further detail anexample implementation of a reader/capacity sensor coupled to an exampletreatment housing in accordance with some embodiments; and

FIGS. 37A-37K are diagrams illustrating relative positions andorientations between a capacity sensing antenna and treatment media inaccordance with various embodiments of a combined reader/capacity sensorin accordance with some embodiments.

The figures are not necessarily to scale. Like numbers used in thefigures refer to like components. However, it will be understood thatthe use of a number to refer to a component in a given figure is notintended to limit the component in another figure labeled with the samenumber.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Some embodiments disclosed herein involve non-contact detection,authentication, and/or identification of treatment cartridges and/orother removable components. The disclosed approaches involve a detectionmember that, when electromagnetically excited, induces a magneticresponse corresponding to a code that can be used to detect,authenticate and/or identify the cartridge.

FIG. 1A is a conceptual diagram illustrating a treatment cartridge 100that includes a detection member 150 in accordance with someembodiments. The cartridge 100 can be inserted into and/or fluidicallycoupled with a host device 200, shown in FIG. 2A, such as a refrigeratoror other such appliance. Fluid flow features of the cartridge 100 can beconfigured to control fluid flow through treatment media 103 disposedwithin the interior volume 104 of the cartridge 100. The cartridge 100may have a fluid inlet 111 to receive fluid to be treated from the hostdevice 200 and a fluid outlet 121 to provide treated fluid to the hostdevice 200. The cartridge 100 includes a housing 101 comprising one ormore walls 102 that enclose an interior volume 104 in which a treatmentmedia 103 and/or fluid can be contained. In some embodiments, thecartridge 100 has a closed end 105. The material of the cartridge 100 istypically non-conductive, at least in the vicinity of the detectionmember 150. The cartridge 100 may comprise a non-conducting materialsuch as a polymer, ceramic, rubber, or glass. Examples of suitablepolymers include polypropylene, polyethylene, and polycarbonate. In someembodiments, the resistivity of the cartridge 100 is higher than about 1ohm-m. In other embodiments, the resistivity of the cartridge 100 ishigher than 10³ ohm-m. In still other embodiments, the resistivity ofthe cartridge 100 is higher than 10⁸ ohm-m.

A detection member 150 is shown in a detection area 160 of the cartridge100. The detection member 150 may be formed on or within the cartridge100 and/or may be attached to a surface of the cartridge 100, e.g., onan exterior or interior surface of the cartridge 100, or within thesurfaces of the cartridge 100. The detection member includes at leastone closed electrically conductive loop 151 that includes at least twospatially separated sections. When at least one loop section iselectromagnetically excited, each loop section generates a magneticresponse comprising a magnetic amplitude and/or a magnetic phaseresponse. The magnetic responses of at least two spatially separate loopsections are predetermined by the physical shape and/or surroundingenvironment of the sections. The magnetic responses of the at least twoloop sections correspond to at least a one digit code.

The closed electrically conductive loop 151 may be positioned at anysuitable location of the cartridge 100, such as on the outer surface ofthe housing 101, within the interior volume 104, within a wall 102 ofthe housing 101, or within electromagnetic contact with the treatmentmedia 103.

The cartridge 100 may include engagement features 131 configured toengage with compatible engagement features 231 of a host device 200 (seeFIG. 2A). When present, the engagement features may serve to align thedetection member 150 with a detection sensor 281 of the host device 200that detects the code generated by the loop sections. The engagementfeatures can be selected from mechanical elements used to couple aremovable treatment cartridge to a manifold. Such engagement featurescan include: threaded connections, a bayonet connection; a radiallyextending lug such as a ramped lug, a helical lug, or a Z-thread lug; alongitudinally extending fluid cartridge inlet prong and alongitudinally extending fluid cartridge outlet prong; a stem extendingfrom the exterior housing with the fluid cartridge inlet and the fluidcartridge outlet, the stem can be either circular, oval, or other shape;a quarter-turn connection; or a lug with an arcuate bottom surface thatacts as an engaging cam to lock the treatment cartridge onto themanifold. The connection between the cartridge 100 and the host device200 may include a spool valve connection, for example.

Alternatively, a replaceable treatment cartridge having a detectionmember can be placed into a suitable reusable enclosure. In thisembodiment, the cartridge housing is typically replaced with a porousexterior member and one or more endcaps are used to direct the fluidwithin the reusable enclosure through the treatment media.

Suitable treatment media include activated carbon; filtering media suchas paper, nonwovens, woven fabric, porous membranes; ion exchangeresins; ultra violet light; reverse osmosis membranes. The treatmentmedia is configured to remove one or more of chemical agents such aschlorine, chloramine, ozone, and chlorine dioxide, lead, particulates,VOCs. In general, filtration media may be used in a broad range ofapplications involving filtration, separation, and purification offluids (liquid and gas). Example media includes, although is not limitedto, water filtration media, activated carbon, modified activated carbon,catalytic carbon, carbon, charcoal, titanium dioxide, silica, clays,polymers, non-wovens, electrets, air filtration media, waterdisinfectant removal media, particulate removal media, organic contentremoval, ion-exchange media, reverse osmosis media, iron removal media,semipermeable membranes, molecular sieves, sand, magnets, screens, andbarrier media. Example filtration techniques with which sensorsdescribed herein may be used include, as examples: absorption,chemisorption, physisorption, adsorption, precipitation, sublimation,ion-exchange, exclusion, extraction, electrophoresis, electrolysis,reverse osmosis, barrier membranes, sedimentation, distillation, and gasexchange.

The cartridge 100 may take the three dimensional (3D) form of apolyhedron (cuboids, prisms, pyramids) or a non-polyhedron (spheres,cylinders, cones). In some embodiments, the detection member 150 isaligned to a specific feature of the cartridge 100 defined by its 3Dshape. In some embodiments, the detection member 150 may be aligned toan alignment feature 190 on the cartridge 100. The cartridge 100 maycontain alignment features that enable proper alignment between thecartridge 100 and a filtration manifold 275 (see FIG. 2A) on the hostdevice 200 that provides fluid to be treated to the cartridge 100 viathe device outlet 211 of the manifold 275 and receives treated fluidfrom the cartridge 100 via the device inlet 221 of the manifold 275.

As illustrated in FIG. 1B, the conductive loop 151 comprises anelectrically conductive material 152 arranged as a continuouselectrically conductive loop. The loop 151 has an outer edge 151 a andan inner edge 151 b with electrically conductive material disposedbetween the outer and inner edges 151 a, 151 b. A non-electricallyconductive material 153 is disposed between the inner edge 151 b of theloop 151 and beyond the outer edge 151 a of the loop 151. For example,the non-electrically conductive material 153 may be the material of thecartridge.

The width, w, of the conductive material 152 between the outer 151 a andinner 151 b edges may be substantially uniform or may be non-uniform.The direct current series resistance of the closed conductive loop 151can be less than 10 kohm, 1 kohm, 100 ohm, 50 ohm, or 10 ohm. Theshortest conductive path through the loop 151 may be less than 40 cm, 20cm, 15 cm, or 10 cm and greater than 0 cm. For example, the conductiveloop 151 may comprise an electrically conductive material in the form ofa continuous loop such that if a single conductivity break is introducedanywhere along the conductive path of the loop 151, the real part of theimpedance measured through the remaining conductive path is less than10000 ohms. In some embodiments, the real part of the impedance throughthe conductive path of the broken loop is less than 1000 ohms, 100 ohms,or 50 ohms, or 10 ohms and greater than 0 ohms.

As discussed in more detail below, in some embodiments the conductiveloop a 151 may be arranged in a single layer and may have a singleinductive turn. In some embodiments, the closed conductive loop 151 maybe arranged in multiple layers and may have multiple inductive turns.The loop 151 is configured to inductively couple to the reader 281 ofthe host device 200 (shown in FIG. 2A). The conductive loop 151, basedon its physical nature, behaves as an inductor with an inductance value.To provide a specified amount of coupling and be contained within thephysical size of a treatment cartridge, the maximum inductance of loop151 may be less than about 500 μH, or less than about 200 μH, or lessthan about 100 μH, or less than about 50 μH, or less than about 5 μH, orless than about 1 μH, or less than about 200 nH, or less than about 150nH, or less than about 100 nH, or less than about 50 nH, and greaterthan about 0 nH. To provide a specified amount of coupling, the minimuminductance of loop may be greater than about 1 nH, or greater than about10 nH, or greater than about 20 nH, or greater than about 50 nH, andless than about 500 nH.

The non-conductive area enclosed within the shortest electrical path ofthe closed conductive loop 151 may be greater than about 1 mm², orgreater than about 10 mm², for example. The non-conductive area enclosedwithin the shortest conductive path of the closed conductive loop 151may be less than about 100 cm², or less than about 50 cm², or less thanabout 25 cm², for example. The shortest conductive path of the closedconductive loom may be greater than about 1 cm, or greater than about 2cm. The length of the shortest conductive path of the closed conductiveloop may be less than about 100 cm, less than about 50 cm, less thanabout 34 cm, or less than about 24 cm, or less than about 10 cm.

The electrically conductive loop 151 may be resonant at particularfrequency and may be non-resonant within the transmitting frequencyrange of the transmitting elements of the reader 281 (see FIG. 2A). Asreferred to herein, a non-resonant loop refers to a loop with aself-resonant frequency higher than the transmitting frequency of thetransmitting elements of the reader 281. For example, in someembodiments, the self-resonance of the closed conductive loop 151 isgreater than 30 MHz, 100 MHz, 1 GHz, or 10 GHz and less than about 100GHz.

In some embodiments, the area contained within the inner edge 151 b ofthe loop 151 may be less than about 20 cm², or less than about 10 cm² orless than about 5 cm², and greater than about 100 cm². In someembodiments, all the area of the loop 151 contained within the inneredges 151 b may be contained within a four sided polygon having a firstdimension, l, along a first axis parallel to one of the sides of thepolygon 195 (x-axis in FIG. 1B) and a second dimension, h, along asecond axis perpendicular to the first axis (y-axis in FIG. 1B). For thesmallest such four sided polygon that contains all the area within theinner edge 151 b of the loop, a ratio of the longest of the first andsecond dimensions to the shortest of the first and second dimensions isgreater than about 1.2, or greater than 1.5, or greater than 2.0, orgreater than 3.0, and less than about 10.0.

A hypothetical circle 197 can be inscribed within the inner edge 151 bof the loop 151, wherein in some embodiments a maximum diameter, d, ofthe circle 197 may be larger than 1 mm, 2 mm, or 3 mm. In someembodiments, a diameter, d, of a largest circle 197 that can beinscribed within the inner edge 151 b may be smaller than 20 cm, 10 cm,4 cm, or 2 cm.

A hypothetical straight line segment 196 can be inscribed within theinner edge 151 b of the loop 151. In some embodiments, the longestlength, l, of a straight line segment 196 that can be contained withinthe inner edge 151 b of the loop 151 may be less than 20 cm, 10 cm, 4 cmor 2 cm. In some embodiments, the longest length, l, of a straight linesegment 196 that can be contained within the inner edge 151 b of theloop 151 may be greater than 3 mm, 5 mm, or 1 cm. Ranges of any of theforgoing lengths, l, are possible, such as greater 5 mm and less than 2cm.

The loop 151 may be manufactured via any one or more of several methodsincluding screen printing conductive inks, etching of conductive films,and/or other additive and subtractive methods. Attachment of the loop151 to the cartridge 100 may be achieved through any one or more ofseveral methods including pressure sensitive adhesive, thermallyactivated adhesive, direct printing onto the cartridge, epoxies, and/orincorporating the loop during and/or injection molding of the cartridge.In some embodiments, the conductive loop 151 is attached to thecartridge 100 in such a way that removal of the conductive loop from thecartridge may result in one or more electrical breaks in the loop.

The cartridge 100 may have any suitable shape, for example, thecartridge 100 may have a substantially polyhedral shape, a substantiallynon-polyhedral shape, e.g., a cylindrical shape, depending on theapplication in which the cartridge is used. As illustrated in FIG. 1A,cartridge 100 extends along a longitudinal axis indicated by dashed line199 in FIG. 1A and has a circumference in a plane, represented by dashedline 198, that is perpendicular to the longitudinal axis 199.

In various embodiments, the closed conductive loop 151 may traverse lessthan about 20%, 30%, 50%, 70% of the circumference of the cartridge 100and/or may traverse more than about 2%, 10%, 20%, 30%, 40% of thecircumference of the cartridge 100. In various embodiments the closedconductive loop 151 may traverse less than about 20%, 30%, or 50% of thelength of the cartridge 100 and/or may traverse more than about 2%, 10%,20%, 30%, or 40% of the length of the cartridge 100.

In some embodiments, the length of the detection area 160 may be greaterthan or equal to the length of the conductive loop 151. The length ofthe detection area 160 can be correlated to the length of the sensorarray of a reader as discussed in more detail below. For example, thelength of the conductive loop 151 may be about equal to the length ofthe detection area or may be less than about 75%, or less than about50%, or less than about 25%, or less than about 10%, or less than about5%, or less than about 1% of the length of the detection area.

FIG. 2A is a conceptual diagram that shows the cartridge 100 of FIG. 1Afluidically, mechanically, and inductively coupled to the host device200. The host device 200 includes a host device fluid outlet 211configured to be fluidically coupled with the cartridge inlet 111 and ahost device fluid inlet 221 configured to be fluidically coupled to thecartridge outlet 121. The host device fluid outlet 211 supplies fluid tobe treated to the cartridge 100 through the cartridge fluid inlet 111and the host device fluid inlet 221 receives treated fluid from thecartridge fluid outlet 121. The engagement features of the cartridge andthe appliance 131, 231 align the detection area 160 of the cartridge 100with the reader 281 of the host device 200.

The detection member 150 and the reader 281 form a detection system 280,as illustrated in FIGS. 2A and 2B. The detection member 150 is a passivedevice that can operate without a power source. In some embodiments, thereader 281 includes a power source 283 that provides power for operationof the reader 281. The reader 281 includes an array 250 of at least twosensor elements 251 a-d and associated detection circuitry 260.

The sensor elements may comprise a coil or loop that senses the magneticresponse signal of the conductive loop 151. For example, each sensorelement may be or comprise one or more of a single turn inductor, amulti-turn inductor, a two-dimensional conductive loop, a conductiveloop with three dimensional features, and a capacitive element. Thesensor elements may be resonant or non-resonant. The detection member150 and/or conductive loop 151 are positioned relative to the array ofsensor elements 251 a-d of the reader 281. The sensor elements 215 a-dmay be positioned at any location where at least one sensor element canelectromagnetically excite the loop 151 and the magnetic response of atleast another section of the loop can be detected by at least one of thesensor elements. In some embodiments, one or more of the sensor elements251 a-d may be located adjacent to the loop 151, e.g., above or belowthe loop and/or to one side of the loop. For example, some of the sensorelements may be located at a first side of the loop and other sensorelements located adjacent to a second side of the loop. In someembodiments, one or more of the sensor elements 251 a-d may comprise acoil or loop that surrounds the loop 151.

The length and/or arrangement of the detection area 160 and/or theconductive loop 151 may be correlated with the number and/or arrangementof the sensor elements of the reader. In some embodiments, the detectionarea 160 includes sections that do not include loop sections. Detectionarea sections that do not include loop sections result in a relativelylow amplitude signal sensed by the corresponding sensor elements of thereader as discussed in more detail below.

A transceiver 285 drives at least one sensor element to operate as anelectromagnetic signal transmitter and receives a sensed signal from atleast one sensor element. In some embodiments, the transceiver 285 mayinclude separate drive and sense circuitry for each of the sensorelements such that any of the sensor elements can function as atransmitter element and any of the sensor elements can function as areceiver element. In some embodiments, two or more drive circuits and/ortwo or more sense circuits may be multiplexed to various transmitterand/or receiver elements.

The transceiver 285 drives at least one element of the sensor array totransmit an electromagnetic signal, e.g., a radio frequency (RF) signal.When the detection member 150 is in communication range of the reader281 and is electromagnetically excited by the transmitted signal fromthe reader, the detection member 150 magnetically couples to at leastsome of the sensor elements of the array. The signal transmitted fromthe reader 281 electromagnetically excites at least one section of theloop. The electromagnetic excitement generates a magnetic phase and/oramplitude response in each of the spatially separate loop sections. Themagnetic phase and/or amplitude response of the loop sections generatessignals from the loop sections onto sensor elements of array 250. Themagnetic phase and/or amplitude responses of the loop sectionscorrespond to a code which is represented in the signals of the sensorelements.

The physical nature of the sensor elements causes coupling between thetransmitter element and the receiver elements in the absence of theclosed loop 151 of the detection member 150. This coupling will cause asignal baseline to be measured on one or more sensor elements. Themagnetic amplitude response of the conductive loop causes a signalrepresented by an increase or decrease to this baseline signal. Thus,the magnetic amplitude response of a loop section generates a signal ora change in signal on a corresponding sensor element of the reader thatencodes a code digit in the amplitude of the signal. In someembodiments, a decreased or increased magnetic amplitude responsecorresponds to a decreased or increased coupled signal between the loopsection with its corresponding sensor element.

A magnetic phase response of a loop section generates a signal on acorresponding sensor element of the reader that encodes a code digit inthe phase of the signal. In some embodiments, a magnetic phase responsecorresponds to phase shift between a magnetic response of a loop sectionwith respect to the phase of the magnetic response of the loop sectionthat is electromagnetically excited. The transceiver 285 receives thesignals from the outputs of the sensor elements. The signals receivedfrom the sensor elements are processed by signal processing circuitry,such as a microcontroller 284 implementing stored instructions, toextract the one or more code digits.

In various embodiments, the code may be represented by the amplitude orphase of an analog signal, the amplitude or phase of an RF signal, orthe amplitude or phase of a digital signal. The code may be expressed ina numeral system having any radix or base, e.g., binary, ternary, octal,decimal, hexadecimal, etc.

The code is at least a one digit code that can be used by themicrocontroller to verify that a compatible cartridge has been insertedinto the host device. The code can be used to verify that the cartridgehas been positioned correctly and/or is otherwise properly installed inthe host device. If not, the detection system circuitry may generate orwithhold a signal that prevents start-up of the host device, preventsfluid flow through the cartridge, and/or warns a user via a userinterface 286 that no cartridge is installed, an unauthenticatedcartridge has been installed and/or that the cartridge is not properlyinstalled. In some embodiments, the code may identify the cartridgeand/or provide other information about the cartridge, e.g., modelnumber, identification number, flow rate, type of cartridge, expirationdate, etc.

In some embodiments, any one or more of the sensor elements may beoperated as transmitter elements and any one or more sensor elements maybe operated as receiver elements. In some embodiments, authentication ofthe cartridge may be verified by operating different sensor elements astransmitters and receivers during separate time periods. For example, afirst sensor element may be operated as a receiver and a second sensorelement operated as a transmitter during a first time period toauthenticate the cartridge. In a second time period, the second sensorelement is operated as a receiver and the first sensor element isoperated as a transmitter. The signals received by the first and secondsensor elements during the first and second time periods, respectively,are used, separately or in combination, to determine a ratio of signalamplitudes or relative phase.

Embodiments disclosed herein enable low cost detection members, allowinglow cost, non-contact electronic authentication of components installedin a host device. FIG. 3 illustrates a replaceable cartridge 301inserted in a manifold 302 of a host device. The replaceable cartridge301 comprises a non-conductive treatment housing, fluid flow controlfeatures, and treatment media contained within the cartridge andconfigured to treat the fluid passing through the cartridge 301.

The cartridge 301 includes a detection member comprising a single closedconductive loop 351 in this example. The manifold 302 includes a readercomprising a transmitter element 361 that transmits an electromagneticsignal, e.g., a radio frequency (RF) signal and a sensor element 362.When the cartridge 301 is inserted in the manifold, the loop 351 ispositioned relative to the sensor elements 361, 362. The transmittedelectromagnetic signal from the transmitter element 361electromagnetically excites the loop 351. A current induced in the loop351 by the electromagnetic signal generates a predetermined magneticresponse in the loop. The magnetic response of the loop 351 generates acurrent (or voltage) signal on the sensor element 362. Reader circuitry363 drives the transmitter element 361 to transmit the RF signal andreceives and processes the signal generated on the sensor element 362.

The presence of the conductive loop 351 when the replaceable treatmentcartridge 301 is inserted into filtration manifold 302 modifies thecoupling between the transmitter element 361 and the sensor element 362when compared to a situation where no loop is present. The modifiedcoupling, and thus the presence of the loop 351, is discernible in thesignal generated on the sensor element 362 from the loop 351. In theexample illustrated in FIG. 3, the signal on sensor element 362represents a one digit code that indicates the presence or absence ofthe loop.

FIG. 4 shows a graph 401 of the amplitude of a signal transmitted fromtransmitter element 361, a graph 402 of the baseline signal on sensorelement 362 when the loop 351 is not present, and a graph 403 of thesignal generated from the loop on sensor element 362 when the loop 351is present. The amplitude of the signal on the sensor element 362increases with the presence of the loop 351. In some implementations,the single loop detection member illustrated by FIGS. 3 and 4 may beused to provide a 1 bit binary code indicating presence “1” or absence“0” of the cartridge.

A near-field coupled signal between the conductive loop 351 and thesensor elements 361, 362 are identifiable in the signal generated fromthe loop in the sensor element 362, allowing the reader circuitry 363detect a presence of the cartridge 301 inserted into the filtrationmanifold 302 by analyzing the signal of the sensor element 362.Furthermore, misalignment and/or other improper insertion of thecartridge 301 into the filtration manifold 302 may change the couplingbetween the loop 351 and the sensor elements 351, 362 and thus changethe signal generated from the loop 351. The reader circuitry 363 mayanalyze the signal on the sensor element 362 to determine if thecartridge 301 is present and/or is properly inserted into the filtrationmanifold 302. In some implementations, discussed in more detail herein,the geometrical configuration of the loop may allow for the magneticresponse of spaced apart loop sections and signals generated by the loopsections to represent a code that includes additional information aboutthe cartridge such as cartridge identification (model number, serialnumber) and/or cartridge classification (media type, maximum volume,flow rate).

As illustrated in FIGS. 3 and 4, in some embodiments the conductive loopmay take the form of a single inductive turn loop. A single inductiveturn loop provides the ability to fabricate the loop on a single layerwithout the need to have a crossover feature, resulting in a lower costmanufacturing process and increased reliability.

The physical shape, configuration, and/or orientation of the conductiveloop may provide additional complexity and capability to the detectionsystem. Although more complex and may result in the detection member andsensors to incur additional manufacturing cost, the difficulty to defeatthe authentication and the ability to classify and/or identifycomponents upon which the detection member is attached, may besignificantly increased.

The spatial arrangement of sections of the loop within the detectionarea is a representation of a code that may be visually observed and/orcan be electronically detected when the loop is electromagneticallyexcited to generate magnetic phase and/or amplitude responses in theloop sections and to generate signals from the loop sections.

FIG. 5A illustrates a component 1 having a detection member 10comprising at least one closed electrically conductive loop having atleast two spaced apart loop sections 11 a, 11 b. In the example of FIG.5A, the spaced apart loop sections 11 a, 11 b are arranged respectivelyin spaced apart sections 12 a, 12 b of a detection area 12 of thecomponent 1. FIG. 5A illustrates a host device 2 having a detectionsensor 20 capable of detecting the code of the detection member 10. Thedetection sensor 20 includes a sensor array 21 comprising sensorelements 21 a and 21 b that correspond to the sections 11 a, 11 b of theclosed conductive loop 10. The detection sensor 20 includes detectioncircuitry 22 configured to drive one or more of the sensor elements 21a, 21 b to transmit an electromagnetic signal and to receive sensedsignals from one or more of the sensor elements 21 a, 21 b. Thedetection sensor 20 and the detection member 10 together form adetection system 50 which is enclosed by the dashed line in FIG. 5A.

When the component 1 and the host device 2 are within communicationrange of the detection system 50, the transmitted signal fromtransmitter element 21 a electromagnetically excites at least onesection 11 a, 11 b of the closed conductive loop 11. When at least onesection 11 a, 11 b of the loop 11 is electromagnetically excited, eachloop section 11 a, 11 b generates a predetermined magnetic responsewhich may be a magnetic amplitude response, a magnetic phase response,or both. The magnetic amplitude and/or phase responses of one or more ofthe loop sections 11 a, 11 b correspond to at least a one digit code.The magnetic amplitude and/or phase response of at least one loopsection 11 a, 11 b generates a signal on a corresponding sensor element21 a, 21 b. The signal on the corresponding sensor element 21 a, 21 brepresents the code.

In any of the embodiments described herein, the detection memberdisclosed herein may be used to detect, authenticate, classify, and/oridentify a component that is used with a host device. In someembodiments, the detection member may sense a state of the component,such as the capacity of the component, upon which it is attached. Thedetection member and detection sensor may be used in a variety ofapplications where a disposable replacement element or article ischanged to restore or renew a system's operation. Applications arenumerous and can include, a filter bag component of a host devicevacuum, a water treatment cartridge in a water treatment facility, afilter for a furnace, an air filter for a personal protection device,ink cartridges in a printer, tinting cartridges in a paint mixingsystem; caulking cartridge in a gun, cartridge in a dispenser, adhesivefilm in a dispenser, disposable paint cups on a spray gun, liquidcolorant container for an injection molding machine, abrasive member fora grinding or sanding machine, cartridges for mixing machines thatcontain substances such as epoxies, body fillers, dental moldings,adhesives, or sealants, an air filter component in an automobile, a cardkey component with a host lock, etc. The detection member hasapplicability to any disposable/replaceable article configured to beinserted into or placed near a reusable receptacle.

Geometrical features of sections of the loop and/or the spatialarrangement of the loop sections can provide more complex codes thatinclude multiple code digits. In some configurations, the extent of eachloop section can be defined by one or more geometrical features of theloop. For example, some geometrical features may be disposed at theboundaries between loop sections, e.g., cross over features as depictedin FIG. 6A and/or some geometrical features may be disposed within theloop sections, e.g., notch features as depicted in FIG. 7A. Theboundaries of the loop sections may be defined by the loop features. Forexample, a loop feature, such as a cross over feature or narrow notchmay be disposed at a loop section boundary. Loop features such as anotch, branch, electrically conductive island and/or peninsula may bedisposed within a loop section and correspond to a width of the loopsection.

Embodiments discussed below present three digit code configurations asexamples. It will be appreciated that the approaches discussed hereinmay be used to provide more or fewer digits of information. Furthermore,to simplify the illustrations, the detection area sections, loopsections, and sensor elements discussed herein are linearly arranged.However, the approaches are not constrained to linear arrangement of thedetection area sections, loop sections and/or sensor elements, and twodimensional, three dimensional and/or non-linear arrangements are alsopossible and are encompassed by this disclosure.

As described in more detail below, in embodiments discussed herein atleast one conductive loop is arranged in a detection area of thecomponent, the detection area including one or more detection areasections. Each detection area section corresponds to a sensor element ofthe reader. In some implementations, the device may include indicatorfeatures that indicate the boundaries of the detection area and/orindicate the boundary of each detection area section. Such indicatorfeatures may include any type of indicator, e.g., indicators that areprinted, molded, adhesively attached, or otherwise affixed to thedevice.

The closed conductive loop includes one or more loop sectionsrespectively disposed in at least some of the detection area sections.The number of loop sections may be less than or equal to the number ofdetection area sections. A magnetic response generated by a first loopsection disposed in a first detection area section may differ or besubstantially the same as a magnetic response generated in a second loopsection in a second section of the detection area. In someconfigurations, no loop section is included in some detection areasections, therefore there is no magnetic response generated in thesedetection area sections, resulting in a low or zero amplitude signalrelative to the baseline signal on the sensor element corresponding tothe detection area section with no loop section.

FIG. 5B shows a portion of a detection system 500 including a sensorarray 560 with four sensor elements 561, 562, 563, 564 and a detectionmember comprising a closed electrically conductive loop 550 disposedwithin a detection area 540. In this embodiment, the detection area 540includes four detection area sections 541, 542, 543, 544. The loop 550includes three loop sections 551, 552, 553. Loop section 553 is disposedin detection area section 544; loop section 552 is disposed in detectionarea section 543; loop section 551 is disposed in detection area section542; and no loop section is disposed in detection area section 541. Eachdetection area section 541-544 corresponds to one sensor element561-564, respectively, and is physically proximate to its correspondingsensor element 561-564. Detection area section 544, which contains loopsection 553, is proximate to sensor element 564 which is thetransmitting element in this embodiment. Detection area sections 541through 543 correspond respectively to receiver elements 561 through563.

When loop section 553 is electromagnetically excited by anelectromagnetic signal transmitted by the transmitter element 564, acurrent is induced in the loop 550 causing each loop section 551-553 togenerate a predetermined magnetic response. Current (or voltage) signalsare generated by induction from the loop sections 552, 551 ontocorresponding sensor elements 562, 563 due to the magnetic responses ofthe loop sections 552, 551. There is no loop section in detection areasection 541, thus no signal is generated from a loop section on sensorelement 561 from detection area section 541.

The predetermined magnetic responses generated by loop sections 551 and552 in detection area sections 542 and 543 and the lack of a magneticresponse in detection area section 541 with no loop section correspondto a code. The code is represented in relatively high amplitude signalsgenerated by induction from detection area sections 542 and 543 ontosensor elements 562 and 563 and a relatively low amplitude signalgenerated from detection area section 541 onto sensor element 561.

The magnetic responses generated by loop sections 551 and 552 indetection area sections 542 and 543 increases the coupled signal betweenthe transmit sensor element 564 and receive sensor elements 562 and 563relative to the coupled signal of detection area section 541 with noloop section and thus no magnetic response. The increased coupled signalresults in relatively high amplitude electromagnetic signals on sensorelements 562 and 563. The relatively high amplitude received signals areinterpreted by the reader circuitry (not shown in FIG. 5B) as a logiclevel 1. The coupling between the transmitter element 564 and the sensorelement 561 in detection area section 541 is relatively low and thus thesignal generated on sensor element 561 is relatively low. The relativelylow amplitude signal on sensor element 561 is interpreted by the readercircuitry as a logic level 0. Thus, when the magnetic response indetection area section 541 and the signal on sensor element 561 aredesignated as the least significant bit (LSB) of the code and themagnetic response in detection area 543 and the signal on sensor element563 are designated as the most significant bit (MSB) of the code, thespatial arrangement of the loop sections and their magnetic responses inthe detection area sections correspond to the binary code 110, ordecimal 6, which is represented in the signals from sensor elements561-563.

Geometrical features of the closed conductive loop can cause differentpredetermined magnetic phase and/or amplitude responses to be generatedin different spaced apart sections of the loop when the loop iselectromagnetically excited. The different phase and/or magnituderesponses correspond to a code that is represented in signals generatedon the sensor elements from the loop sections. In the presence of anelectromagnetic field, current is induced in the loop in a directionthat creates an opposing magnetic field. The induced current in the loopis dependent on the coupling of the loop with the transmitting elementof the detection sensor. The size, shape and/or orientation features ofthe loop relative to the individual sensor elements modifies near-fieldcoupling locally between the loop sections and the corresponding sensorelements. The loop sections may have varying coupling coefficients withcorresponding sensor elements due to the geometrical features of theloop sections. The loop sections may be visibly identified by thepresence of local size, shape, and orientation variations of the loopsections, although this may not always be possible.

In some scenarios, the loop may include at least one of a phase shiftingfeature such that when the loop is electromagnetically activated theloop generates a first magnetic phase response in one or more firstsections of the loop and generates a second magnetic phase response inone or more second sections of the loop. For example, the first magneticphase response and the second magnetic phase response may be separatedin phase by 180°.

As an example, the phase shifting feature may comprise a crossoverfeature 610 of the loop 600 as illustrated in FIGS. 6A and 6B. As shownin the cross section of FIG. 6B, at the crossover 610, a first portion613 of the loop 600 crosses over a second portion 611 of the loop 600with an electrically insulating material 612 separating the crossoverportions 611, 613. In some embodiments, the electrically insulatingmaterial 612 may be air.

The loop 600 of FIG. 6A includes four sections 600 a-d, where, section600 a corresponds to the transmitter element of the reader (not shown inFIG. 6A) that electromagnetically excites the loop 600 at loop section600 a. When loop section 600 a is electromagnetically excited, a currentis induced the loop 600 that generates a magnetic field opposing thetransmitted electromagnetic signal. The magnetic phase response ofsection 600 b is in phase (0° phase shift) with respect to the magneticfield generated in section 600 a. The signal generated from section 600b on its corresponding sensor element of the reader (not shown in FIG.6A) has a 0° phase shift with respect to the transmitted electromagneticsignal representing the 0° phase shift of the magnetic response of loopsection 600 b. The angular direction of the current in the loop 600changes, e.g., substantially reverses, at the cross over 610 causing themagnetic phase response of loop sections 600 c and 600 d to have a 180°phase shift with respect to loop section 600 a. The signal generatedfrom sections 600 c and 600 d on corresponding sensor elements of thereader (not shown in FIG. 6A) are shifted in phase from the transmittedelectromagnetic signal by 180°, representing the 180° phase shift of themagnetic response of sections 600 c and 600 d relative to 600 a. Thephase of the magnetic response of the loop sections can correspond to acode, e.g., 180° phase shift may be interpreted as a logic 1 and 0°phase shift may be interpreted as a logic zero, for example. The code isrepresented in the phase shift of the signals generated on the sensorelements by the loop sections 600 b-600 d.

The current (or voltage) signals induced on the sensor elements from theloop sections depend on the local coupling between the loop sections andthe corresponding sensor elements. Local coupling between loop sectionsand corresponding sensor elements depends on the separation distancebetween the loop section and the corresponding sensor element, the shapeof the loop section relative to the shape of the sensor element, and/orthe angular orientation of the loop section relative to the angularorientation of the sensor element.

For example, lower coupling may be achieved by designing a loop sectioncoupling to a corresponding sensor element which results in a smallersignal generated on the corresponding sensor element from the loopsection. Higher coupling may be achieved by designing a loop sectioncoupling to a corresponding sensor element which results in a largersignal generated from the loop section on the corresponding sensorelement. Higher coupling can be achieved by making the area of a loopsection more similar to the area of a corresponding sensor element andlower coupling can be achieved by making the area of a loop section lesssimilar to the area of a corresponding sensor element. Making the areaof the loop section less similar to the area of the corresponding sensorelement can be achieved by making the area of the loop section smalleror larger. The area of a loop section is bounded by inner edges of theconductive loop and/or by one or more borders of the adjacent loopsections.

In some scenarios, the loop may include at least one amplitude changingfeature that increases or decreases the amplitude of the sensor signalgenerated by the magnetic amplitude response of at least one section ofthe loop relative to a similarly constructed loop section without thefeature. The relative increase or decrease in the generated sensorsignal is dependent on the on geometrical similarity between the loopsection and its corresponding sensor element, wherein geometricalsimilarity or correspondence connotes that the shape and area of theperimeter of the loop section is similar to the shape and area of theperimeter of the sensor element and the loop section substantiallyoverlaps the sensor element. Relatively larger or smaller amplitudesignal on the sensor element may occur because the amplitude changingfeature causes the size and/or shape of the loop section to correspondmore or less closely with the size and/or shape of the sensor element asillustrated in FIGS. 7-9.

One or more notched sections of the loop can affect the coupling betweenthe notched loop sections and their corresponding sensor elements andthus affects signals generated from the notched loop sections. The sizeand/or shape of the notches may cause the loop sections to correspondmore or less closely with the corresponding sensor elements whencompared to a similarly constructed loop section that is not notched.Thus, the size and/or shape of the notches may result in a magneticamplitude response of the notched sections that generate signals oncorresponding sensor elements that are larger or smaller than signalsgenerated by similarly constructed un-notched loop sections.

The loop 700 shown in FIG. 7A includes four loop sections 700 a-d ofsubstantially equal width that extend linearly along the x direction inloop 700, where section 700 a corresponds to the position of thetransmitter element of the reader (not shown in FIG. 7) thatelectromagnetically excites the loop 700. The current induced in theloop by the electromagnetic signal transmitted by the transmitterelement generates a predetermined magnetic amplitude response in eachloop section. Signals are generated from the loop sections 700 b-700 drespectively onto three sensor elements (not shown in FIG. 7A). Thesignals represent the magnetic amplitude responses of the loop sections700 b-700 d. FIG. 7A loop 700 has a notch 710 that extends for somedistance along the x-axis across loop section 700 c. For example, thenotch 710 may extend along the x-axis across the loop by at least about10%, 25%, 50%, or 75% of loop section 700 c. The notch 710 may extendalong the x-axis across substantially all, e.g., more than about 95%, ofthe loop section 700 c as shown in FIG. 7A. The depth, h2, of the notch710 along the y-axis may be more than about 10%, 25%, 50%, or 75% butless than 100% of the maximum height, h1, of the loop 700.

The non-electrically conductive area between the inner edge 702 of theloop in sections 700 b and 700 d is larger than the non-electricallyconductive area between the inner edge 702 of loop section 700 c. Forexample, the area of notched loop section 700 c may be less than 95%,75%, 50%, 25% or 10% but greater than 0% of the area of loop section 700b. In further examples, the area of notched loop section 700 c may beless than 4 cm², or less than 2 cm², or less than 1 cm², or less than 5mm².

The notch 710 may cause the geometry of the loop section 700 c tocorrespond more or less closely to the sensor element corresponding toloop section 700 c. For example, FIG. 7B shows sensor elements 721 b-721d above loop sections 700 b-700 d. As illustrated, the geometry ofsensor elements 721 b and 721 d corresponds more closely with thegeometry of loop sections 700 b and 700 d and the geometry of sensorelement 721 c corresponds less closely with the geometry of loop section700 c when compared to the geometrical correspondence of sensor elements721 b, 721 d and loop sections 700 b, 700 d. Coupling between loopsections 700 b and 700 d and corresponding sensor elements 721 b and 721d is higher than the coupling between loop section 700 c and sensorelement 721 c due to the closer geometrical correspondence. Thus, themagnetic amplitude response of loop section 700 c generates a relativelylower amplitude signal on sensor element 721 c and the magneticamplitude responses of loop sections 700 b and 700 d generate relativelyhigher amplitude signals on loop sections 731 b and 731 d, respectively.If a “0” value is assigned to a relatively lower amplitude signal and a“1” value assigned to a relatively higher amplitude signal, an n-bitidentification number can be determined by the reader via binarydecoding of the signals induced on the sensor elements where n is equalto the number of loop sections −1. The magnetic amplitude responses ofthe loop sections and thus the amplitude of the generated signals ontothe sensor elements may be multi-level, providing a tertiary,quaternary, or higher order code.

A different scenario is illustrated in FIG. 7C, wherein higher couplingis achieved between notched loop section 700 c and corresponding sensorelement 731 c due to closer geometrical correspondence. The un-notchedloop sections 700 b and 700 d have lower coupling with theircorresponding sensor elements 731 b and 731 d. Thus, the magneticamplitude response of loop section 700 c generates a relatively largeramplitude signal on sensor element 731 c and the magnetic amplituderesponses of loop sections 700 b and 700 d generate relatively loweramplitude signals on sensor elements 731 b and 731 d, respectively.

A branch in a loop section may cause the coupling between the loopsection and its corresponding sensor element to be increased ordecreased relative to the coupling of similarly constructed butunbranched loop sections.

The loop 800 shown in FIG. 8A includes four equal width loop sections800 a-d that extend linearly along the x direction in FIG. 800, wheresection 800 a corresponds to the position of the transmitter element ofthe reader (not shown in FIG. 8) that electromagnetically excites theloop section 800 a. For simplicity of explanation, equal width loopsections are represented in the diagrams, however, it will beappreciated that in some embodiments, loop sections of unequal widthsmay be used.

The transmitted electromagnetic signal induces a current through theconductive loop 800 that generates a predetermined magnetic amplituderesponse in each loop section 800 b-800 d. Signals are generated fromthe loop sections 800 b-800 d onto three sensor elements which are notshown in FIG. 8A. The signals represent the coupling of magneticamplitude responses of the loop sections 800 b-800 d with theircorresponding sensor elements.

Loop 800 has a branch feature 810 comprising two loop branches 810 a,810 b that extend for some distance along the x-axis across loop section800 c. For example, the branch feature 810 may extend along the x-axisacross more than 10%, 25%, 50%, or 75% of loop section 800 c. The branchfeature 810 may extend along the x-axis across substantially all, e.g.,more than 95%, of the loop section 800 b as shown in FIG. 8A. The depth,h3, of the lower branch 810 a along the y-axis may be more than 10%,25%, 50%, or 75% but less than 100% of the maximum height, h1, of theloop 800.

The two branches 810 a, 810 b are electrically connected in parallel andthus the current in the branch feature is divided between the twobranches 810 a, 810 b. A first area of loop section 800 c betweenfurthest inner edge 802 b of the branch feature 810 and inner edge 802is equal to the areas of loop sections 800 b and 800 d. A second area ofloop section 800 c between closest inner edges 802 a of the branchfeature and inner edge 802 is smaller than the areas of loop sections800 b and 800 d. For example, the second area of branched loop section800 c may be less than 95%, 75%, 50%, 25% or 10% but greater than 0% ofthe area of the loop sections 800 b or 800 d.

As illustrated in FIG. 8B, where the area of the sensor elements 821 b,821 d is similar to the area of loop sections 800 b, 800 d, the divisionof current between the two branches 810 a, 810 b in loop section 800 ccauses the coupling of loop section 800 c with its corresponding sensorelement 821 c to be relatively smaller when compared to the coupling ofsections 800 b and 800 d with their respective sensor elements 821 b and821 d. The relatively lower coupling of loop section 800 c with itscorresponding sensor element 821 c causes the magnetic response of loopsection 800 c when electromagnetically excited to generate a relativelylower amplitude signal on sensor element 821 c. The relatively highercoupling of loop sections 800 b and 800 d with sensor elements 821 b and821 d, respectively, cause the magnetic response of loop sections 800 band 800 d to generate relatively higher amplitude signals on theircorresponding sensor elements 821 b and 821 d.

Alternatively, as shown in FIG. 8C, a relatively higher coupling may beachieved between branched loop section 800 c and its correspondingsensor element when the geometry of inner edges 802 a and 802 hasgreater similarity to the geometry of the corresponding sensor elementwhen compared to the geometrical correspondence of un-branched loopsections 800 b and 800 d and their corresponding sensor elements. Therelatively higher coupling of loop section 800 c with its correspondingsensor element 831 c causes the magnetic response of loop section 800 cwhen electromagnetically excited to generate a relatively higheramplitude signal on sensor element 831 c. The relatively lower couplingof loop sections 800 b and 800 d with sensor elements 831 b and 831 d,respectively, cause the magnetic response of loop sections 800 b and 800d when electromagnetically excited to generate relatively loweramplitude signals on their corresponding sensor elements 831 b and 831d.

FIGS. 9A and 9B illustrate an embodiment in which notches in a loopsection can cause inductive coupling between the notched loop sectionwith its corresponding sensor element to be greater than the inductivecoupling between other un-notched loop sections and their respectivesensor elements. The greater inductive coupling is due to the notchedloop section having greater geometrical correspondence with itscorresponding sensor element when compared to a similarly constructedun-notched loop section.

The loop 900 shown in FIG. 9A includes four equal width loop sections900 a-d that extend linearly along the x direction in FIG. 9A, wheresection 900 a corresponds to the position of the transmitter element ofthe reader (not shown in FIG. 9A) that electromagnetically excites theloop 900. The induced current through the conductive loop results in apredetermined magnetic response in each loop section 900 b-900 d.Signals are generated from the loop sections 900 b-900 d respectivelyonto three sensor elements (not shown in FIG. 9A). The signals representcoupling of the magnetic responses of the loop sections 900 b-900 d withtheir respective elements 931 b-931 d.

In this example, loop 900 includes notches 911, 912 that each extend forsome distance along the x-axis across loop section 900 b. Although twonotches are shown, fewer or more than two notches may be present in aloop section. The notches 911, 912 may be positioned at or near theborders of the loop section. As shown in FIG. 9A, notch 911 ispositioned within loop section 900 b at the border of loop section 900 band loop section 900 a. Notch 912 is positioned within loop section 900b at the border of loop section 900 b and loop section 900 c. Forexample, a notch 911, 912 may extend along the x-axis across the loopsection 900 b less than about 50%, or less than about 25%, or less thanabout 10% of loop section 900 b. For example, a notch 911, 912 mayextend along the y-axis across the loop section 900 b more than 10%,25%, 50%, or 75% but less than 100% of loop section 900 b.

As shown in FIG. 9A, a largest circle that will fit within inner edgesof the shortest conductive path of the closed conductive loop 900 in anun-notched section, such as section 900 d, has diameter d1. A largestcircle that will fit within the inner edges of the shortest conductivepath of the closed conductive loop 900 in a notched section, such assection 900 b has diameter d2, where d1>d2. The largest circle that willfit within the inner edges of the closed conductive loop 900 in thenotched section may have diameter d2 which is less than about 3 cm.

As shown in FIG. 9B, in this embodiment, the notches 911, 912 cause theperimeter of the loop section 900 b to correspond more closely to theperimeter of the sensor element corresponding to loop section 900 b whencompared to un-notched sections 900 c and 900 d. Loop sections 900 b-900d would have equal areas but for the notches in loop section 900 b whichreduces the area of loop section 900 b. The area of loop section 900 bis bounded by the inner edge 902 of the loop 900 and by loop section 900a to the left and loop section 900 c to the right. The area of loopsection 900 c is bounded by the inner edge 902 of the loop 900 and byloop section 900 b to the left and loop section 900 d to the right. Thearea of loop section 900 d is bounded by the inner edge 902 of the loop900 and by loop section 900 c to the left.

As illustrated in FIG. 9B, the perimeter of sensor element 931 bcorresponds more closely with the perimeter of loop section 900 b andthe perimeters of sensor elements 931 c and 931 d when compared to theperimeter correspondence of loop sections 900 c and 900 d. Couplingbetween loop sections 900 b and 900 d and corresponding sensor elements931 c and 931 d may be lower than the coupling between loop section 900b and sensor element 931 b due to the closer perimeter similarity ofloop section 900 b and sensor element 931 b. The relatively lowercoupling of loop sections 900 c and 900 d with their correspondingsensor elements 931 c, 931 d causes the magnetic responses of loopsections 900 c and 900 d to generate a relatively lower amplitude signalon corresponding sensor elements 931 c and 931 d when loop section 900 ais electromagnetically excited. The relatively higher coupling of loopsection 900 b with corresponding sensor element 931 b causes themagnetic response of loop section 900 b to generate a relatively higheramplitude signal on corresponding sensor element 931 b when loop section900 a is electromagnetically excited.

The magnetic amplitude response of the loop section can depend at leastin part on the number of inductive turns within the loop section. Notethat a loop section that includes more than one inductive turn willrequire a cross over. The inducted signal on the receiving sensorelement relative to the transmitted signal depends on the turns rationbetween loop sections coupled to the transmitter element and to thesensor element.

FIG. 10 depicts a loop 1000 having four equal width loop sections 1000a-1000 d that extend linearly along the x direction in FIG. 10, wheresection 1000 a corresponds to the position of the transmitter element ofthe reader (not shown in FIG. 10) that electromagnetically excites theloop 1000, inducing a current through the conductive loop 1000. Theinduced current generates a predetermined magnetic amplitude response ineach loop section 1000 b-1000 d. Signals are generated from the loopsections 1000 b-1000 d respectively onto three sensor elements (notshown in FIG. 10). The signals represent the predetermined magneticamplitude responses of the loop sections 1000 b-1000 d.

In this example, loop sections 1000 b and 1000 d are two inductive turnloop sections having a turns ratio with respect to their correspondingsensor elements of 1:2. Loop section 1000 c is a single inductive turnsection, having a turns ratio with respect to its corresponding sensorelement of 1:1. When electromagnetically excited, the magnetic amplituderesponse of the 1:2 turns ratio loop sections 1000 b and 1000 d generatea relatively higher signal on their corresponding sensor elementswhereas the magnetic amplitude response of the 1:1 turns ratio loopsection 1000 c generates a relatively smaller signal on itscorresponding sensor element. The signals generated from the loopsections 1000 b-1000 d represent a code that corresponds to the magneticamplitude response of the loop sections 1000 b-1000 d.

A loop may include at least one masking feature that reduces themagnetic amplitude response inside the loop section relative tosimilarly constructed loop sections that do not include a maskingfeature, modify the inductance or capacitance of a coupled sensorelement, or a combination of both. The masking feature may be anelectrically conductive region within the loop section that supportseddy currents which can be induced by the transmitted electromagneticsignal. The eddy currents are disposed within the shortest conductivepath of the closed conductive loop. The area of an electricallyconductive area may be at least about 10%, or at least about 20% or atleast about 30%, or at least about 50%, and less than about 70% or lessthan about 80%, or less than about 90% of the non-conductive areaencompassed by the loop section.

FIG. 11 shows a closed electrically conductive loop having four equalwidth loop sections 1100 a through 1100 d extending along the x-axis.Loop section 1100 a is positioned to correspond to the transmitterelement of a reader which is not shown in FIG. 11. The electromagneticsignal transmitted by the transmitter element induces a current in theloop section 1100 a and the induced current generates a magneticamplitude response from loop sections 1100 b through 1100 d.

The electrically conductive region 1110 comprises a conductive peninsulathat modifies the magnetic field of the loop region 1100 c. In thisexample, the conductive region 1110 is electrically connected to theloop, although this need not be the case as illustrated in FIG. 12. Theconductive region 1110 modifies the magnetic response of loop section1100 c and modifies coupling between the loop section 1110 c and itscorresponding sensor element when compared to when compared to similarlyconstructed loop sections 1100 b and 1100 d without a conductive region.The conductive region 1110 may have an area that is greater than 10%,25%, 50%, or 75% but less than 100% of the area of the loop sectionwhich contains it where the area of the loop section is bounded by inneredges 1102 of the loop and/or borders of adjacent loop sections.

A conductive loop may include multiple conductive regions as illustratedby conductive loop 1200 of FIG. 12. Conductive regions may beelectrically connected to the loop or may be electrically disconnectedfrom the loop as illustrated by conductive regions 1211 and 1212 in FIG.12. Loop 1200 includes four equal width loop sections that extend alongthe x-axis where section 1200 a is positioned to correspond to thetransmitter element which is not shown in FIG. 12. The electromagneticsignal from the transmitter element induces a current in the loop 1200that generates magnetic amplitude responses in each of loop sections1200 b, 1200 c, 1200 d. Loop section 1200 b includes a first conductiveregion 1211 and loop section 1200 c includes a second conductive region1212 having a larger area than the area of conductive region 1211.Electromagnetic excitement of the loop 1200 induces a first eddy currentin conductive region 1211 and a second eddy current in conductive region1212. For example, the eddy current in the larger area region 1212 maybe larger than the eddy current in the smaller area region 1211.

The presence of the eddy currents in the conductive regions 1211, 1212of loop sections 1200 b and 1200 c can decrease the magnetic amplituderesponse of loop sections 1200 b, 1200 c relative to a similarlyconstructed loop section 1200 d that does not include a conductiveregion. The decrease in magnetic amplitude response corresponds todecreased coupled signal between loop sections 1200 b, 1200 c and theircorresponding sensor elements. Furthermore, the magnetic response ofloop section 1200 c is decreased relatively more than the magneticresponse of loop section 1200 b due to the larger eddy current in region1212 of loop section 1200 c compared with the smaller eddy current inregion 1211 of loop section 1200 b. Signals generated from the loopsections 1200 b, 1200 c, 1200 d on corresponding sensor elementsrepresent the magnetic amplitude responses of the loop sections 1200 b,1200 c, 1200 d. In this example, loop section 1200 d would generate asignal having the relatively highest amplitude on its correspondingsensor element that could be interpreted as level 2 of a tertiary code,loop section 1200 c would generate a signal having the relatively lowestamplitude signal on its corresponding sensor element that could beinterpreted as level 0 of the tertiary code, and loop section 1200 bwould generate a signal having an amplitude between that of the signalsgenerated by loop section 1200 b and loop section 1200 d that could beinterpreted as level 1 of the tertiary code.

FIGS. 13 through 15 illustrate operation of detection members thatgenerate magnetic phase and/or amplitude responses corresponding tocodes when the detection members are electromagnetically excited. FIGS.13 through 15 illustrate detection members comprising one or more closedelectrically conductive loops disposed in a detection area of acomponent. FIGS. 13 through 15 also illustrate a portion of a hostdevice comprising a reader including sensor elements where a transmitterelement transmits an electromagnetic signal to excite the loop sectionsand signals are generated onto sensor elements in accordance with themagnetic responses of the loop sections.

In each of the examples of FIGS. 13 through 15, the magnetic phase andamplitude responses of the loop sections correspond to a three digitbinary code which is represented in the phase and amplitude of thesignals generated from the respective loop sections. Although a threedigit binary code is illustrated in these examples, it will beappreciated that the code could have more or fewer digits. Althoughbinary codes are illustrated, tertiary, quaternary, or higher ordercodes could be implemented. For example, the magnetic amplituderesponses of the loop sections could have three, four, or moredesignated magnetic amplitude response levels and the correspondingelectromagnetic signals generated by the loop sections could have three,four, or more designated amplitude levels to implement a tertiaryquaternary, or higher code.

In the embodiments shown in FIGS. 13A through 13G, each of the closedconductive loops 1311-1317 extends linearly with four spatiallyseparated loop sections. One loop section is arranged closest to thetransmitter element and is electromagnetically excited by thetransmitter element. The loops include at least one cross over featurethat shifts the phase of the magnetic phase response of a loop sectionrelative to the phase of the magnetic response of theelectromagnetically excited loop section (the leftmost loop section) andshifts the phase of the signals generated on the sensor elementsrelative to the phase of the transmitted electromagnetic signal.Typically the section boundary will pass through a crossover feature,but this is not necessarily the case.

In each example provided in FIGS. 13A through 13G, a logic level 1 isassigned to a magnetic phase response of a loop section with asubstantially 180° phase shift relative to the loop section coupled tothe transmitter element which is the leftmost loop section in eachexample. The 180° phase shift of the magnetic phase response results ina 180° phase shift between the signal generated from the loop section onits corresponding sensor element and the transmitted signal. A logiclevel 0 is assigned to a magnetic phase response of a loop section witha 0° phase shift relative to the loop section coupled to the transmitterelement. The 0° phase shift of the magnetic phase response results in a0° phase shift between the signal generated from the loop section on itscorresponding sensor element and the transmitted signal. A logic level 0is also assigned to a low (or zero) amplitude signal on a sensorelement. In these examples, the signal on the rightmost sensor element1330 d is designated as corresponding to the least significant bit (LSB)of the code and the signal on the leftmost sensor element 1330 b isdesignated as corresponding to the most significant bit (MSB) of thecode.

FIG. 13A illustrates a portion of a component that includes a detectionmember comprising a closed conductive loop 1311 disposed within adetection area 1321 of the component. FIG. 13A also illustrates aportion of a host device comprising reader 1330 including sensorelements 1330 a-1330 d.

Detection area 1321 includes four spatially separated detection areasections 1321 a, 1321 b, 1321 c, 1321 d in this example. Loop 1311includes two spatially separate loop sections 1311 a, 1311 b disposedrespectively in detection area sections 1321 a, 1321 b with a cross overfeature 1341 disposed between loop sections 1311 a and 1311 b.Electromagnetic excitation of the first loop section 1311 a by anelectromagnetic signal transmitted from the transmitter element 1330 ainduces a current in the first loop section 1311 a that generates amagnetic field in the first loop section 1311 a that opposes themagnetic field of the transmitted electromagnetic signal. The cross overfeature 1341 reverses the direction of the current through loop section1311 b, shifting the phase of the magnetic response in the second loopsection 1311 b from that of the first loop section 1311 a by 180°. Asignal is generated on sensor element 1330 b from the second loopsection, wherein the signal on sensor element 1330 b is shifted in phaseby 180° with respect to the transmitted signal due to the cross overfeature 1340.

There are no loop sections in detection area sections 1321 c and 1321 dcausing the signal on sensor elements 1330 c and 1330 d to have a low orzero amplitude. In this particular example, a logic level 1 is assignedto signal with a 180° phase shift relative to the transmitted signal; alogic level 0 is assigned to a signal with a 0° phase shift relative tothe transmitted signal; and a logic level 0 is assigned to a signal withlow or zero amplitude. With this interpretation, the signals on thesensor elements 1330 b-1330 d represent the three digit binary code 100,or decimal 4, where the signal on sensor element 1330 d is designated ascorresponding to the least significant bit (LSB) of the code and thesignal on sensor element 1330 b is designated as corresponding to themost significant bit (MSB) of the code.

FIG. 13B illustrates a portion of a component that includes a detectionmember comprising a closed conductive loop 1312 disposed within adetection area 1321 of the component. FIG. 13B also illustrates aportion of a host device comprising a reader 1330. Closed conductiveloop 1312 includes three spatially separate loop sections 1312 a, 1312b, 1312 c disposed respectively in detection area sections 1321 a, 1321b, 1321 c with a cross over feature 1342 disposed between loop sections1312 b and 1312 c. Electromagnetic excitation of the first loop section1312 a by an electromagnetic signal transmitted from the transmitterelement 1330 a induces a current and a corresponding magnetic field inthe first loop section 1312 a that opposes the magnetic field of thetransmitted electromagnetic signal. Current induced in the second loopsection 1312 b generates a magnetic response that has a 0° phase shiftwith respect to the magnetic field in the first loop section 1312 a. Theelectromagnetic signal generated by loop section 1312 b on sensorelement 1330 b has a phase shift of 0° with respect to the signaltransmitted by sensor element 1330 a. The cross over feature 1342reverses the angular direction of the current through loop section 1312c, shifting the phase of the magnetic response in the third loop section1312 c in accordance with the right-hand rule from that of the firstloop section 1312 a and second loop section 1312 b by 180°. The thirdloop section 1312 c generates a signal on sensor element 1330 c that isshifted in phase by 180° with respect to the transmitted signal due tothe cross over feature 1342. There is no loop section in detection areasection 1321 d causing the signal on sensor element 1330 d to be low orzero. A logic level 1 is assigned to a sensor element signal with a 180°phase shift relative to the transmitted signal; a logic level 0 isassigned to a sensor signal with a 0° phase shift relative to thetransmitted signal; and a logic level 0 is assigned to sensor signalwith low amplitude. The signals on the sensor elements 1330 b-1330 dcorrespond to the three digit binary code 010, or decimal 2, where thesignal on sensor element 1330 d is designated as corresponding to theleast significant bit (LSB) of the code and the signal on sensor element1330 b is designated as corresponding to the most significant bit (MSB)of the code.

FIG. 13C illustrates a portion of a component that includes a detectionmember comprising a closed conductive loop 1313 disposed within adetection area 1321 of the component. FIG. 13C also illustrates aportion of a host device comprising a reader 1330. Closed conductiveloop 1313 includes three spatially separate loop sections 1313 a, 1313b, 1313 c disposed respectively in detection area sections 1321 a, 1321b, 1321 c with a cross over feature 1343 disposed between loop sections1313 a and 1313 b. Electromagnetic excitation of the first loop section1313 a by an electromagnetic signal transmitted from the transmitterelement 1330 a induces a current in the first loop section 1313 a thatcauses a magnetic field opposing the magnetic field of the transmittedelectromagnetic signal. Current in the second loop section 1313 bgenerates a magnetic response of the second loop section 1313 b that hasa 180° phase shift with respect to the magnetic field of the first loopsection 1313 a due to the cross over feature 1343 disposed between thefirst 1313 a and second 1313 b loop sections. The signal generated bythe second loop section 1313 b on sensor element 1330 b has a phaseshift of 180° with respect to the signal transmitted by sensor element1330 a due to the cross over feature 1343. The magnetic response of thethird loop section 1313 c is also shifted in phase from the magneticfield of the first loop section 1313 a by 180° due to the cross overfeature 1343. The third loop section 1313 c generates an electromagneticsignal on sensor element 1330 c that is shifted in phase by 180° withrespect to the transmitted signal due to the cross over feature 1343.There is no loop section in detection area section 1321 d causing thesignal on sensor element 1330 d to be low or zero. A logic level 1 isassigned to a signal on a sensor element with a 180° phase shiftrelative to the transmitted signal; a logic level 0 is assigned to asignal on a sensor element with a 0° phase shift relative to thetransmitted signal; and a logic level 0 is assigned to a signal on asensor element with low amplitude. The signals on sensor elements 1330b-1330 d correspond to the three digit binary code 110, or decimal 6,where the signal on sensor element 1330 d is designated as correspondingto the least significant bit (LSB) of the code and the signal on sensorelement 1330 b is designated as corresponding to the most significantbit (MSB) of the code.

FIG. 13D illustrates a portion of a component that includes a detectionmember comprising a closed conductive loop 1314 disposed within adetection area 1321 of the component. FIG. 13D also illustrates aportion of a host device comprising a reader 1330. Closed conductiveloop 1314 includes four spatially separate loop sections 1314 a, 1314 b,1314 c, 1314 d disposed respectively in detection area sections 1321 a,1321 b, 1321 c, 1321 d with a cross over feature 1344 disposed betweenloop sections 1314 c and 1314 d. Electromagnetic excitation of the firstloop section 1314 a by an electromagnetic signal transmitted from thetransmitter element 1330 a induces a current in the loop which generatesa corresponding magnetic field in the first loop section 1314 a thatopposes the magnetic field of the electromagnetic signal. The magneticresponse of loop section 1314 b has a 0° phase shift with respect to themagnetic field of the first loop section 1314 a. The electromagneticsignal generated by loop section 1314 b on sensor element 1330 b has aphase shift of 0° with respect to the signal transmitted by sensorelement 1330 a. The a magnetic response of loop section 1314 c that hasa 0° phase shift with respect to the magnetic field of the first loopsection 1314 a. The electromagnetic signal generated by loop section1314 c on sensor element 1330 c has a phase shift of 0° with respect tothe signal transmitted by sensor element 1330 a.

The direction of the current flow in the loop is reversed in the fourthloop section 1314 d relative to the direction of current in the firstloop section 1314 a due to the cross over feature 1344. Current in thefourth loop section 1314 d generates a magnetic response that has a 180°phase shift with respect to the magnetic field of the first loop section1314 a. The signal generated by loop section 1314 d on sensor element1330 d has a phase shift of 180° with respect to the signal transmittedby sensor element 1330 a due to the cross over feature 1344. A logiclevel 1 is assigned to sensor signal with a 180° phase shift relative tothe transmitted signal and a logic level 0 is assigned to a sensorsignal with a 0° phase shift relative to the transmitted signal. Thesignals on the sensor elements 1330 b-1330 d correspond to the threedigit binary code 001, or decimal 1, where the signal on sensor element1330 d is designated as corresponding to the least significant bit (LSB)of the code and the signal sensed by sensor element 1330 b is designatedas corresponding to the most significant bit (MSB) of the code.

FIG. 13E illustrates a portion of a component that includes a detectionmember comprising a closed conductive loop 1315 disposed within adetection area 1321 of the component. FIG. 13E also illustrates aportion of a host device comprising a reader 1330. Closed conductiveloop 1315 includes four spatially separate loop sections 1315 a, 1315 b,1315 c, 1315 d disposed respectively in detection area sections 1321 a,1321 b, 1321 c, 1321 d. Closed conductive loop 1315 includes multiplecross over features including a first cross over feature 1345 a disposedbetween loop sections 1315 a and 1315 b, a second cross over feature1345 b disposed between loop sections 1315 b and 1315 c, and a thirdcross over feature 1345 c disposed between loop sections 1315 c and 1315d.

Electromagnetic excitation of the first loop section 1315 a by anelectromagnetic signal transmitted from the first sensor element 1330 ainduces a current that results in a magnetic field in the first loopsection 1315 a that opposes the magnetic field of the transmittedelectromagnetic signal. Current in the second loop section 1315 breverses angular direction of current relative to the current in thefirst loop section 1315 a due to the first cross over feature 1345 a.Current in the second loop section 1315 b generates a magnetic responsethat has a 180° phase shift with respect to the magnetic field of thefirst loop section 1315 a. The signal generated from loop section 1315 bonto sensor element 1330 b has a phase shift of 180° with respect to thesignal transmitted by sensor element 1330 a.

Current in the third loop section 1315 c reverses angular directionrelative to the current in the second loop section 1315 b due to thesecond cross over feature 1345 b. Current in the third loop section 1315c generates a magnetic response that has a 360° (0°) phase shift withrespect to the magnetic field of the first loop section 1315 a. Thesignal generated from loop section 1315 c onto sensor element 1330 c hasa phase shift of 0° with respect to the signal transmitted by sensorelement 1330 a.

Current in the fourth loop section 1315 d reverses angular directionrelative to the current in the third loop section 1315 c due to thethird cross over feature 1345 c. Current in the fourth loop section 1315d generates a magnetic response in the fourth loop section 1315 d thathas a 540° (180°) phase shift with respect to the magnetic field of thefirst loop section 1315 a. The signal generated from loop section 1315 donto sensor element 1330 d has a phase shift of 180° with respect to thesignal transmitted by sensor element 1330 a.

A logic level 1 is assigned to a signal on a sensor element with a 180°phase shift relative to the transmitted signal and a logic level 0 isassigned to a signal on a sensor element with a 0° phase shift relativeto the transmitted signal. The signals on the sensor elements 1330b-1330 d correspond to the three digit binary code 101, or decimal 5,where the signal on sensor element 1330 d is designated as correspondingto the least significant bit (LSB) of the code and the signal sensed bysensor element 1330 b is designated as corresponding to the mostsignificant bit (MSB) of the code.

FIG. 13F illustrates a portion of a component that includes a detectionmember comprising a closed conductive loop 1316 disposed within adetection area 1321 of the component. FIG. 13F also illustrates aportion of a host device comprising a reader 1330. Closed conductiveloop 1316 includes four spatially separate loop sections 1316 a, 1316 b,1316 c, 1316 d disposed respectively in detection area sections 1321 a,1321 b, 1321 c, 1321 d. Closed conductive loop 1316 includes a crossover feature 1346 disposed between loop sections 1316 b and 1316 c.

Electromagnetic excitation of the first loop section 1316 a by anelectromagnetic signal transmitted from the first sensor element 1330 ainduces a current that results in a magnetic field in the first loopsection 1316 a that opposes the magnetic field of the transmittedelectromagnetic signal. Current in the second loop section 1316 b hasthe same angular direction as current in loop section and generates amagnetic response in the second loop section 1316 b with a 0° phaseshift with respect to the magnetic field of the first loop section 1316a. The signal generated from loop section 1316 b onto sensor element1330 b has a phase shift of 0° with respect to the signal transmitted bysensor element 1330 a.

Current in the third loop section 1316 c reverses angular directionrelative to the current in the second loop section 1316 b due to thesecond cross over feature 1346. Current in the third loop section 1316 cgenerates a magnetic response that has a 180° phase shift with respectto the magnetic field of the first loop section 1316 a. The signalgenerated from loop section 1316 c onto sensor element 1330 c has aphase shift of 180° with respect to the signal transmitted by sensorelement 1330 a.

Current in the fourth loop section 1316 d travels in the same angulardirection as the current in the third loop section 1316 c. Current inthe fourth loop section 1316 d generates a magnetic response in thefourth loop section 1316 d that has a 180° phase shift with respect tothe magnetic field of the first loop section 1316 a. The signalgenerated from loop section 1316 d onto sensor element 1330 d has aphase shift of 180° with respect to the signal transmitted by sensorelement 1330 a.

A logic level 1 is assigned to a signal on a sensor element with a 180°phase shift relative to the transmitted signal and a logic level 0 isassigned to a signal on a sensor element with a 0° phase shift relativeto the transmitted signal. The signals on the sensor elements 1330b-1330 d correspond to the three digit binary code 011, or decimal 3,where the signal on sensor element 1330 d is designated as correspondingto the least significant bit (LSB) of the code and the signal sensed bysensor element 1330 b is designated as corresponding to the mostsignificant bit (MSB) of the code.

FIG. 13G illustrates a portion of a component that includes a detectionmember comprising a closed conductive loop 1317 disposed within adetection area 1321 of the component. FIG. 13G also illustrates aportion of a host device comprising a reader 1330. Closed conductiveloop 1317 includes four spatially separate loop sections 1317 a, 1317 b,1317 c, 1317 d disposed respectively in detection area sections 1321 a,1321 b, 1321 c, 1321 d. Closed conductive loop 1317 includes cross overfeature 1347 between loop sections 1317 a and 1317 b.

Electromagnetic excitation of the first loop section 1317 a by anelectromagnetic signal transmitted from the first sensor element 1330 ainduces a current that results in a magnetic field in the first loopsection 1317 a that opposes the magnetic field of the transmittedelectromagnetic signal. Current in the second loop section 1317 breverses angular direction relative to the current in the first loopsection 1317 a due to the first cross over feature 1347. Current in thesecond loop section 1317 b generates a magnetic response that has a 180°phase shift with respect to the magnetic field of the first loop section1317 a. The signal generated from loop section 1317 b onto sensorelement 1330 b has a phase shift of 180° with respect to the signaltransmitted by sensor element 1330 a.

Current in the third loop section 1317 c travels in the same angulardirection relative to the current in the second loop section 1317 b.Current in the third loop section 1317 c generates a magnetic responsethat has a 180° phase shift with respect to the magnetic field of thefirst loop section 1317 a. The signal generated from loop section 1317 conto sensor element 1330 c has a phase shift of 180° with respect to thesignal transmitted by sensor element 1330 a.

Current in the fourth loop section 1317 d travels in the same angulardirection relative to the current in the second and third loop sections1317 b, 1317 c. Current in the fourth loop section 1317 d generates amagnetic response in the fourth loop section 1317 d that has a 180°phase shift with respect to the magnetic field of the first loop section1317 a. The signal generated from loop section 1317 d onto sensorelement 1330 d has a phase shift of 180° with respect to the signaltransmitted by sensor element 1330 a.

A logic level 1 is assigned to a signal on a sensor element with a 180°phase shift relative to the transmitted signal and a logic level 0 isassigned to a signal on a sensor element with a 0° phase shift relativeto the transmitted signal. The signals on the sensor elements 1330b-1330 d correspond to the three digit binary code 111, or decimal 7,where the signal on sensor element 1330 d is designated as correspondingto the least significant bit (LSB) of the code and the signal sensed bysensor element 1330 b is designated as corresponding to the mostsignificant bit (MSB) of the code.

In the embodiments shown in FIGS. 14A through 14G, a detection area 1421extends linearly and includes four spatially separated sections 1421a-1421 d. A closed conductive loop 1411-1417 includes two, three, orfour spatially separated loop sections, each loop section disposed in adetection area section. One loop section is arranged closest to thetransmitter element 1430 a and is electromagnetically excited by thetransmitter element. The loops 1412, 1414-1416 include at least one loopsection with a notch feature. The notch feature reduces the magneticamplitude response of the loop section and reduces the amplitude of thesignal generated from the loop section on the corresponding sensorelement relative to similarly constructed loop sections that do notinclude a notch feature.

In each example provided in FIGS. 14A through 14G, a logic level 1 isassigned to a relatively high magnetic amplitude response and arelatively high amplitude sensor signal. A logic level 0 is assigned toa relatively low magnetic amplitude response and a relatively lowamplitude sensor signal. In these examples, the magnetic response of therightmost loop section 1411 d-1417 d and the signal on the rightmostsensor element 1430 d are designated as corresponding to the leastsignificant bit (LSB) of the code. The magnetic response of the secondto the leftmost loop section 1411 b-1417 b and the signal on theleftmost sensor element 1430 b are designated as corresponding to themost significant bit of the code.

FIG. 14A illustrates a detection member comprising a closed conductiveloop 1411 that includes two spatially separate loop sections 1411 a,1411 b disposed respectively in detection area sections 1421 a, 1421 b.Electromagnetic excitation of the first loop section 1411 a by anelectromagnetic signal transmitted from the transmitter element 1430 ainduces a current in the loop 1411. In response to the electromagneticexcitement, loop section 1411 b generates a predetermined magneticamplitude response and a signal is generated from loop section 1411 bonto sensor element 1430 b. The magnetic amplitude response of loopsection 1411 b is higher than the magnetic responses of loop sections1411 c and 1411 d which have no loop sections. The amplitude of thesignal on sensor 1430 b is relatively higher than the low or zeroamplitude signals on sensor elements 1430 c and 1430 d. The magneticamplitude response from the loop section 1411 a arranged in thedetection area 1421 and the signals on the sensor elements 1430 b-1430 drepresent the three digit binary code 100, or decimal 4.

FIG. 14B illustrates a detection member comprising a closed conductiveloop 1412 that includes three spatially separate loop sections 1412a-1412 c disposed respectively in detection area sections 1421 a-1421 cwith a notch feature in loop section 1412 b that reduces the magneticamplitude response of loop section 1412 b relative to loop section 1412c. Electromagnetic excitation of the first loop section 1412 a by anelectromagnetic signal transmitted from the transmitter element 1430 ainduces a current in the loop 1412. The induced current generatespredetermined magnetic amplitude responses in loop sections 1412 b and1412 c. The magnetic amplitude response of loop section 1412 b, whichhas a notch, is relatively low when compared with the magnetic amplituderesponse of loop section 1412 c without a notch feature. The signalgenerated on sensor element 1430 b from loop section 1412 b is arelatively low amplitude signal when compared with the relatively highersignal generated on sensor element 1430 c from loop section 1412 c.Detection area section 1421 d has no loop section and thus the signalgenerated on sensor element 1430 d is a relatively low amplitude signal.The magnetic amplitude responses from the loop sections 1412 b through1412 c arranged in the detection area 1421 and the signals on the sensorelements 1430 b-1430 d correspond to the three digit binary code 010, ordecimal 2.

FIG. 14C illustrates a detection member comprising a closed conductiveloop 1413 that includes three spatially separate loop sections 1413a-1413 c disposed respectively in detection area sections 1421 a-1421 c.Electromagnetic excitation of the first loop section 1413 a by anelectromagnetic signal transmitted from the transmitter element 1430 ainduces a current in the loop 1413. The induced current generatespredetermined magnetic amplitude responses in loop sections 1413 b and1413 c that are relatively higher than magnetic amplitude response ofdetection area section 1421 d which includes no loop section. Thesignals generated on sensor elements 1430 b and 1430 c from loopsections 1413 b and 1413 c, respectively, are higher amplitude signalswhen compared with the signal on sensor element 1430 d. The magneticamplitude responses from the loop sections 1413 b through 1413 carranged in the detection area 1421 and the signals on the sensorelements 1430 b-1430 d correspond to the three digit binary code 110, ordecimal 3.

FIG. 14D illustrates a detection member comprising a closed conductiveloop 1414 that includes four spatially separate loop sections 1414a-1414 d disposed respectively in detection area sections 1421 a-1421 dwith notch features in loop sections 1414 b and 1414 c that reduce themagnetic amplitude responses of loop sections 1414 b and 1414 c relativeto loop section 1414 d. Electromagnetic excitation of the first loopsection 1414 a by an electromagnetic signal transmitted from thetransmitter element 1430 a induces a current in the loop 1414. Theinduced current generates predetermined magnetic amplitude responses inloop sections 1414 b through 1414 d. The magnetic amplitude responses ofloop sections 1414 b and 1414 c, which have a notch, are relatively lowwhen compared with the magnetic amplitude response of loop section 1414d without a notch. The signals generated on sensor elements 1430 b and1430 c from loop sections 1414 b and 1414 c, respectively, arerelatively low amplitude signals when compared with the relativelyhigher amplitude signal generated on sensor element 1430 d from loopsection 1414 d. The magnetic amplitude responses from the loop sections1414 b through 1414 d arranged in the detection area 1421 and thesignals on the sensor elements 1430 b-1430 d correspond to the threedigit binary code 001, or decimal 1.

FIG. 14E illustrates a detection member comprising a closed conductiveloop 1415 that includes four spatially separate loop sections 1415a-1415 d disposed respectively in detection area sections 1421 a-1421 dwith notch features in loop section 1415 c that reduces the magneticamplitude responses of loop section 1415 c relative to the magneticamplitude responses of loop sections 1415 b and 1415 d. Electromagneticexcitation of the first loop section 1415 a by an electromagnetic signaltransmitted from the transmitter element 1430 a induces a current in theloop 1415. The induced current generates predetermined magneticamplitude responses in loop sections 1415 b through 1415 d. The magneticamplitude responses of loop section 1415 c, which has a notch, isrelatively low when compared with the magnetic amplitude responses ofloop sections 1415 b and 1415 d which do not have notches. The signalgenerated on sensor element 1430 c from loop section 1415 c isrelatively a low amplitude signal when compared with the relativelyhigher amplitude signals generated on sensor elements 1430 b and 1430 dfrom loop section 1415 b and 1415 d, respectively. The magneticamplitude responses from the loop sections 1415 b through 1415 darranged in the detection area 1421 and the signals on the sensorelements 1430 b-1430 d correspond to the three digit binary code 101, ordecimal 5.

FIG. 14F illustrates a detection member comprising a closed conductiveloop 1416 that includes four spatially separate loop sections 1416a-1416 d disposed respectively in detection area sections 1421 a-1421 dwith a notch feature in loop section 1416 b that reduces the magneticamplitude response of loop section 1416 b relative to loop sections 1416c and 1416 d. Electromagnetic excitation of the first loop section 1416a by an electromagnetic signal transmitted from the transmitter element1430 a induces a current in the loop 1416. The induced current generatespredetermined magnetic amplitude responses in loop sections 1416 bthrough 1416 d. The magnetic amplitude response of loop section 1416 b,which has a notch, is relatively low when compared with the magneticamplitude responses of loop sections 1416 c and 1416 d which do not havenotches. The signal generated on sensor element 1430 b from loop section1416 b is a relatively a low amplitude signal when compared with therelatively higher amplitude signals generated on sensor elements 1430 cand 1430 d from loop sections 1416 c and 1416 d, respectively. Themagnetic amplitude responses from the loop sections 1416 b through 1416d arranged in the detection 1421 and the signals on the sensor elements1430 b-1430 d correspond to the three digit binary code 011, or decimal3.

FIG. 14G illustrates a detection member comprising a closed conductiveloop 1417 that includes four spatially separate loop sections 1417a-1417 d disposed respectively in detection area sections 1421 a-1421 d.None of the loop sections include notches in this example.Electromagnetic excitation of the first loop section 1417 a by anelectromagnetic signal transmitted from the transmitter element 1430 ainduces a current in the loop 1417. The induced current generatespredetermined magnetic amplitude responses in loop sections 1417 bthrough 1417 d. The magnetic amplitude responses of loop sections 1417 bthrough 1417 d are relative high and the signals generated from loopsections 1417 b though 1417 d onto sensor elements 1430 b through 1430d, respectively, are relatively high amplitude signals. The magneticamplitude responses from the loop sections 1417 b through 1417 darranged in the detection area 1421 and the signals on the sensorelements 1430 b-1430 d correspond to the three digit binary code 111, ordecimal 7.

In the embodiments shown in FIGS. 15A through 15G, a detection area 1521extends linearly and includes four spatially separated sections 1521a-1521 d. A closed conductive loop 1511-1517 includes two, three, orfour spatially separated loop sections, each loop section disposed in acorresponding detection area section. One loop section is arrangedclosest to the transmitter element 1530 a and is electromagneticallyexcited by the transmitter element. Each loop 1511-1517 includes atleast one loop section with two inductive turns. The 1:2 turns ratio ofthe 2-turn loop sections increases the magnetic amplitude response ofthe loop section and increases the closed circuit current amplitude ofthe signal generated from the loop section on the corresponding sensorelement relative to similarly constructed loop sections that includeonly one inductive turn.

In each example provided in FIGS. 15A through 15G, a logic level 1 isassigned to a relatively high magnetic amplitude response and arelatively high closed circuit current amplitude sensor signal that isgreater than a baseline signal level. A logic level 0 is assigned to arelatively low magnetic amplitude response and a relatively low closedcircuit current amplitude sensor signal and a sensor signal that is atbaseline signal level. In these examples, the magnetic response of therightmost loop section 1511 d-1517 d and the signal on the rightmostsensor element 1530 d is designated as corresponding to the leastsignificant bit (LSB) of the code. The magnetic response of the secondto the leftmost loop section 1511 b-1517 b and the signal on theleftmost sensor element 1530 b is designated as corresponding to themost significant bit (MSB) of the code.

FIG. 15A illustrates a detection member comprising a closed conductiveloop 1511 that includes two spatially separate loop sections 1511 a,1511 b disposed respectively in detection area sections 1521 a, 1521 b.Electromagnetic excitation of the first loop section 1511 a by anelectromagnetic signal transmitted from the transmitter element 1530 ainduces a current in the loop 1511. In response to the electromagneticexcitement, loop section 1511 b generates a predetermined magneticamplitude response and a signal is generated from loop section 1511 bonto sensor element 1530 b. The loop section 1511 b has twice as manyturns as loop section 1511 a, providing a 1:2 turns ratio, therefore themagnetic amplitude response of loop section 1411 b is relatively higherthan a loop section with a 1:1 turns ratio, and is higher than abaseline (zero) magnetic response for a detection area section with noloop present. Thus the signal generated on sensor element 1530 b fromloop section 1511 b has a higher closed circuit current amplitude whencompared with a signal generated from a 1:1 turns ratio loop section anda higher amplitude than the baseline signal generated on sensor elements1511 c and 1511 d. The magnetic amplitude response from the loop section1511 a arranged in the detection area 1521 and the signals on the sensorelements 1530 b-1530 d represent the three digit binary code 100, ordecimal 4.

FIG. 15B illustrates a detection member comprising a closed conductiveloop 1512 that includes three spatially separate loop sections 1512a-1512 c disposed respectively in detection area sections 1521 a-1521 c.Loop section 1512 b is a 1:1 turns ratio loop section, loop section 1512c is a 1:2 turns ratio section, and detection area section 1521 dincludes no loop section. Electromagnetic excitation of the first loopsection 1512 a by an electromagnetic signal transmitted from thetransmitter element 1530 a induces a current in the loop 1512. Theinduced current generates predetermined magnetic amplitude responses inloop sections 1512 b and 1512 c. The magnetic amplitude response of loopsection 1512 b, which has a 1:1 turns ratio, is relatively lower whencompared with the magnetic amplitude response of 1:2 turns ratio loopsection 1512 c. The magnetic amplitude response of 1:2 turns ratio loopsection 1512 c is relatively higher than the magnetic amplitude responseof the 1:1 turns ratio loop section 1512 b and is higher than thebaseline magnetic response of detection area section 1521 d whichcontains no loop section. The signal generated on sensor element 1530 bfrom loop section 1512 b is a relatively lower closed circuit amplitudesignal when compared with the relatively higher closed circuit amplitudesignal generated on sensor element 1530 c from loop section 1512 c. Thesignal generated on sensor element 1530 c from loop section 1512 c has arelatively higher closed circuit amplitude than the signal on sensorelement 1530 b and is higher than the baseline signal generated onsensor element 1530 d. The magnetic amplitude responses from the loopsections 1512 b through 1512 c arranged in the detection area 1521 andthe signals on the sensor elements 1530 b-1530 d correspond to the threedigit binary code 010, or decimal 2.

FIG. 15C illustrates a detection member comprising a closed conductiveloop 1513 that includes three spatially separate loop sections 1513a-1513 c disposed respectively in detection area sections 1521 a-1521 c.Loop section 1513 b is a 1:2 turns ratio loop section, loop section 1513c is a 1:2 turns ratio loop section, and detection area section 1521 dhas no loop section. Electromagnetic excitation of the first loopsection 1513 a by an electromagnetic signal transmitted from thetransmitter element 1530 a induces a current in the loop 1513. Theinduced current generates predetermined magnetic amplitude responses inloop sections 1513 b and 1513 c that are relatively higher than amagnetic amplitude response of a loop section with a 1:1 turns rationand relatively higher than the baseline magnetic response of detectionarea section 1521 d which includes no loop section. The signalsgenerated on sensor elements 1530 b and 1530 c from loop sections 1513 band 1513 c, respectively, are comparatively higher closed circuitcurrent amplitude signals when compared with the signals from a 1:1 turnratio loop section and are higher than the baseline signal on sensorelement 1530 d. The magnetic amplitude responses from the loop sections1513 b through 1513 c arranged in the detection area 1521 and thesignals on the sensor elements 1530 b-1530 d correspond to the threedigit binary code 110, or decimal 6.

FIG. 15D illustrates a detection member comprising a closed conductiveloop 1514 that includes four spatially separate loop sections 1514a-1514 d disposed respectively in detection area sections 1521 a-1521 d.Loop section 1514 b is a 1:1 turns ratio loop section, loop section 1514c is a 1:1 turns ratio loop section, and loop section 1514 d is a 1:2turns ratio loop section. Electromagnetic excitation of the first loopsection 1514 a by an electromagnetic signal transmitted from thetransmitter element 1530 a induces a current in the loop 1514. Theinduced current generates predetermined magnetic amplitude responses inloop sections 1514 b through 1514 d. The magnetic amplitude responses ofthe 1:1 turns ratio loop sections 1514 b and 1514 c are relatively lowerwhen compared with the magnetic amplitude response of the 1:2 turnsratio loop section 1514 d. The signals generated on sensor elements 1530b and 1530 c from loop sections 1514 b and 1514 c, respectively, arerelatively lower closed circuit current amplitude signals when comparedwith the relatively higher closed circuit current amplitude signalgenerated on sensor element 1530 d from loop section 1514 d. The signalon sensor element 1530 d from loop section 1514 d is higher than thebaseline signal. The magnetic amplitude responses from the loop sections1514 b through 1514 d arranged in the detection area 1521 and thesignals on the sensor elements 1530 b-1530 d correspond to the threedigit binary code 001, or decimal 1.

FIG. 15E illustrates a detection member comprising a closed conductiveloop 1515 that includes four spatially separate loop sections 1515a-1515 d disposed respectively in detection area sections 1521 a-1521 dof detection area 1521. Loop section 1515 b is a 1:2 turns ratio loopsection, loop section 1515 c is a 1:1 turns ratio loop section, and loopsection 1515 d is a 1:2 turns ratio loop section. Electromagneticexcitation of the first loop section 1515 a by an electromagnetic signaltransmitted from the transmitter element 1530 a induces a current in theloop 1515. The induced current generates predetermined magneticamplitude responses in loop sections 1515 b through 1515 d. The magneticamplitude responses of the 1:2 turns ratio loop sections 1515 b and 1515d are relatively high when compared with the magnetic amplituderesponses of 1:1 turns ratio loop section 1515 c. The signal generatedon sensor element 1530 c from loop section 1515 c is relatively a lowerclosed circuit current amplitude signal when compared with therelatively higher closed circuit amplitude signals generated on sensorelements 1530 b and 1530 d from loop section 1515 b and 1515 d,respectively. The signals on sensor elements 1530 b and 1530 d from loopsection 1515 b and 1515 d, respectively, are higher than the baselinesignal. The magnetic amplitude responses from the loop sections 1515 bthrough 1515 d arranged in the detection area 1521 and the signals onthe sensor elements 1530 b-1530 d correspond to the three digit binarycode 101, or decimal 5.

FIG. 15F illustrates a detection member comprising a closed conductiveloop 1516 that includes four spatially separate loop sections 1516a-1516 d disposed respectively in detection area sections 1521 a-1521 dof detection area 1521. Loop section 1516 b is a 1:1 turns ratio loopsection, loop section 1516 c is a 1:2 turns ratio loop section, and loopsection 1516 d is a 1:2 turns ratio loop section. Electromagneticexcitation of the first loop section 1516 a by an electromagnetic signaltransmitted from the transmitter element 1530 a induces a current in theloop 1516. The induced current generates predetermined magneticamplitude responses in loop sections 1516 b through 1516 d. The magneticamplitude response of the 1:1 turns ratio loop section 1516 b isrelatively lower when compared with the magnetic amplitude responses ofloop sections 1516 c and 1516 d which are 1:2 turns ratio loop sections.The signal generated on sensor element 1530 b from loop section 1516 bis a relatively a lower closed circuit current amplitude signal whencompared with the relatively higher closed circuit current amplitudesignals generated on sensor elements 1530 c and 1530 d from loopsections 1516 c and 1516 d, respectively. The signals on sensor elements1530 c and 1530 d have amplitudes that are higher than an amplitude of abaseline signal. The magnetic amplitude responses from the loop sections1516 b through 1516 d arranged in the detection 1521 and the signals onthe sensor elements 1530 b-1530 d correspond to the three digit binarycode 011, or decimal 3.

FIG. 15G illustrates a detection member comprising a closed conductiveloop 1517 that includes four spatially separate loop sections 1517a-1517 d disposed respectively in detection area sections 1521 a-1521 d.Loop sections 1517 b-1517 d are 1:2 turns ratio loop sections.Electromagnetic excitation of the first loop section 1517 a by anelectromagnetic signal transmitted from the transmitter element 1530 ainduces a current in the loop 1517. The induced current generatespredetermined magnetic amplitude responses in loop sections 1517 bthrough 1517 d. The magnetic amplitude responses of loop sections 1517 bthrough 1517 d are relative higher than a magnetic amplitude response ofa 1:1 turns ratio loop section. The signals generated from loop sections1517 b though 1517 d onto sensor elements 1530 b through 1530 d,respectively, are relatively higher closed circuit current amplitudesignals and higher than a baseline signal. The magnetic amplituderesponses from the loop sections 1517 b through 1517 d arranged in thedetection area 1521 and the signals on the sensor elements 1530 b-1530 dcorrespond to the three digit binary code 111, or decimal 7.

The detection member may include two or more two closed conductive loopsas illustrated in FIGS. 16 and 17. In these embodiments, at least twoclosed conductive loops are arranged to be inductively coupled andgalvanically isolated such that there is no direct current flow betweenthe closed conductive loops. FIGS. 16A through 16C show examples ofdetection members comprising multiple inductively coupled, galvanicallyisolated closed conductive loops. FIGS. 16B and 16C illustrate detectionmembers having multiple closed conductive loops wherein at least onesection of the closed conductive loops has a different magnetic phaseresponse when compared with at least one other section of the multipleclosed conductive loops.

FIG. 16A illustrates a detection member 1605 comprising a first closedconductive loop 1610 and a second closed conductive loop 1620 arrangedin a detection area 1630 having three detection area sections 1631,1632, 1633. The first closed conductive loop 1610 is disposed in thefirst detection area section 1631 and the second closed conductive loop1620 is disposed in the second detection area section 1632. No loopsection is disposed in the third detection area section 1633. The firstand second loops 1610, 1620 are galvanically isolated and inductivelycoupled between the first and the second detection area sections 1631,1632. A sensor array 1640 comprising sensor elements 1641, 1642, 1643 isshown proximate and in communication range of the detection member 1605.

The first sensor element 1641 is the transmit sensor in this example.The first sensor element 1641 transmits an electromagnetic signal thatelectromagnetically excites the first loop 1610. The first loop 1610inductively communicates the electromagnetic energy from the transmittedsignal to the second loop 1620, inducing a magnetic response in thesecond loop 1620. The magnetic response of the second loop 1620 has azero degree phase shift with respect to the magnetic response of thefirst loop 1610 which is electromagnetically excited. A signal isgenerated from the second loop 1620 on the second sensor element 1642.The signal on the second sensor element 1642 has zero phase shift withrespect to the electromagnetic signal transmitted from the first element1641. Because the third detection area section 1633 does not include aloop section, no magnetic response is generated in the third detectionarea section 1633 and the signal on the third sensor element 1643 is abaseline low or zero amplitude signal with zero phase shift with respectto the transmitted signal from the first element 1641. In thisparticular example, a 180 degree change in phase from the magneticresponse of the first loop 1610 corresponds to a logical 1 which isrepresented by a 180 degree phase shift of a sensor signal relative tothe phase of the transmitted electromagnetic signal. A 0 degree phaseshift from the magnetic response of the first loop 1610 corresponds to alogical 0 which is represented by a 0 degree phase shift of a sensorsignal relative to the phase of the transmitted electromagnetic signal.A two bit binary code is represented in the signals generated on thesecond 1642 and third 1643 sensor elements from the second 1632 andthird 1633 detection area sections, respectively. When the third sensorelement 1643 is designated as representing the LSB of the code and thesecond sensor element 1642 is designated as representing the MSB of thecode, the code corresponding to the magnetic response of the loops 1610,1620 in the detection area 1630 is 00.

FIG. 16B illustrates a detection member 1606 comprising a first closedconductive loop 1611 and a second closed conductive loop 1621 that arespatially separated and arranged in a detection area 1630 having threedetection area sections 1631, 1632, 1633. The first closed conductiveloop 1621 is disposed in the first detection area section 1631. Thesecond closed conductive loop 1621 includes spatially separate first1621 a and second 1621 b sections. The first section 1621 a of thesecond loop 1621 is disposed in the second detection area section 1632and the second section 1621 b of the second closed conductive loop 1621is disposed in the third detection area section 1633. The first andsecond loops 1611, 1621 are gavantically isolated and are inductivelycoupled between the first 1631 and second 1632 detection area sections.There is a phase shifting cross over 1699 between the first and secondsections 1621 a, 1621 b of the second loop 1621. A sensor array 1640comprising sensor elements 1641, 1642, 1643 is shown proximate and incommunication range of the detection member 1606.

The first sensor element 1641 is the transmit sensor in this example.The first sensor element 1641 transmits an electromagnetic signal thatelectromagnetically excites the first loop 1611. The first loop 1611inductively communicates the electromagnetic energy from the transmittedsignal to the second loop 1621, generating magnetic responses in thefirst and second sections 1621 a, 1621 b of the second loop 1621. Anelectrical signal on the second sensor element 1642 is generated fromthe first section 1621 a of the second loop 1621. The magnetic responseof the first section 1621 a of the second loop 1621 has zero phase shiftwith respect to the phase of the magnetic response of the first loop1611. The signal generated on the second sensor element 1642 has zerophase shift with respect to the electromagnetic signal transmitted fromthe first element 1641. The cross over 1699 reverses the angulardirection of current through the second section 1621 b of the secondloop 1621 and shifts the phase of the magnetic response of the secondsection 1621 b of the second loop 1621 with respect to the phase of themagnetic response of the first loop 1611 by 180 degrees. An electricalsignal is generated on the third sensor element 1643 from the secondsection 1621 b of the second loop 1621 that has a phase shift of 180degrees with respect to the phase of the electromagnetic signaltransmitted from the first element 1641. In this particular example, a180 degree change in phase from the transmitted signal corresponds to alogical 1 and a 0 degree phase shift from the transmitted signalcorresponds to a logical 0. The two bit binary code is represented inthe signals generated on the second 1642 and third 1643 sensor elementsfrom the first and second 1621 a, 1621 b sections, respectively. Whenthe third sensor element 1643 is designated as representing the LSB ofthe code and the second sensor element 1642 is designated asrepresenting the MSB of the code, the code corresponding to the magneticresponse of the loops 1611, 1621 in the detection area 1630 andrepresented by the signals on the second and third sensor elements 1642,1643 is 01.

FIG. 16C illustrates a detection member 1607 comprising a first closedconductive loop 1612 and a second closed conductive loop 1622 that arespatially separated and arranged in a detection area 1630 having threedetection area sections 1631, 1632, 1633. The first closed conductiveloop 1612 includes first 1612 a and second 1612 b spatially separatesections disposed respectively in first 1631 and second 1632 detectionarea sections. There is a cross over phase shifting feature 1698 betweenthe first 1612 a and second 1612 b sections of the first loop 1612. Thesecond closed conductive loop 1622 is disposed in the third detectionarea section 1633. The first and second loops 1612, 1622 aregavantically isolated and are inductively coupled between the second1632 and third 1633 detection area sections. A sensor array 1640comprising sensor elements 1641, 1642, 1643 is shown proximate and incommunication range of the detection member 1607.

The first sensor element 1641 is the transmit sensor in this example.The first sensor element 1641 transmits an electromagnetic signal thatelectromagnetically excites the first loop section 1612 a of the firstloop 1612. The first loop 1612 inductively communicates theelectromagnetic energy from the transmitted signal to the second loop1622. Magnetic responses are generated in the second section 1612 b ofthe first loop 1621 and in the second loop 1622. An electrical signal isgenerated from the second section 1612 b of the first loop 1612 onto thesecond sensor element 1642. The magnetic response of the second section1612 b of the first loop 1612 has a 180 degree phase shift with respectto the phase of the magnetic response of the first section 1612 a of thefirst loop 1612 due to the cross over 1698. The signal generated on thesecond sensor element 1642 from the second section 1612 b of the firstloop 1612 has a 180 degree phase shift with respect to theelectromagnetic signal transmitted from the first element 1641. Thecross over 1698 also shifts the phase of the magnetic response of thesecond loop 1622 with respect to the phase of the magnetic response ofthe first section 1612 a of the first loop 1611 by 180 degrees. Anelectrical signal generated on the third sensor element 1643 from thesecond loop 1622 has a phase shift of 180 degrees with respect to thephase of the electromagnetic signal transmitted from the first element1641. In this particular example, a 180 degree change in phase from themagnetic response of the first section 1612 a of the first loop 1612corresponds to a logical 1 and a 0 degree phase shift from the magneticresponse of the first section 1612 a of the first loop 1612 correspondsto a logical 0. The two bit binary code corresponding to the magneticresponses of the second section 1612 b of the first loop 1612 and thesecond loop 1622 is represented in the signals on the second 1642 andthird 1643 sensor elements. When the third sensor element 1643 isdesignated as representing the LSB of the code and the second sensorelement 1642 is designated as representing the MSB of the code, the codecorresponding to the magnetic responses of the second section 1612 b ofthe first loop 1612 and the second loop 1622 is 11.

FIGS. 17A through 17E show examples of detection members comprisingmultiple inductively coupled, galvanically isolated closed conductiveloops. The loops that are galvanically isolated and inductive coupledlie in different planes, e.g., loops indicated by dashed lines lie in adifferent plane from loops indicated by solid lines. FIGS. 17A and 17Billustrate detection members having multiple closed conductive loopswherein at least one section of the closed conductive loops has adifferent magnetic amplitude response when compared with at least oneother section of the multiple closed conductive loops.

FIG. 17A illustrates a detection member 1701 comprising two spaced apartclosed conductive loops 1711, 1721. The second conductive loop 1721includes two spaced apart sections 1721 a, 1721 b. The first and secondloops 1711, 1721 are arranged in a detection area 1760 having threespaced apart detection area sections 1761, 1762, 1763. The first closedconductive loop 1711 is disposed in the first detection area section1761, the first section 1721 a of the second loop 1721 is disposed inthe second detection area section 1762, and the second section 1721 b ofthe second loop 1721 is disposed in the third detection area section1763. The first and second loops 1711, 1721 are galvanically isolatedand inductively coupled between the first and the second detection areasections 1761, 1762. A sensor array 1770 comprising sensor elements1771, 1772, 1773 is shown proximate and in communication range of thedetection member 1701.

The first sensor element 1771 is the transmit sensor in this example.The first sensor element 1771 transmits an electromagnetic signal thatelectromagnetically excites the first loop 1711. The first loop 1711inductively communicates the electromagnetic energy from the transmittedsignal to the second loop 1721, generating a magnetic response in thefirst and second sections 1721 a, 1721 b of the second loop 1721. Thefirst and second sections 1721 a, 1721 b of the second loop 1712 are twonotched sections in series having a relatively low geometricalcorrespondence with respect to their sensor elements 1772, 1773resulting in a low magnetic amplitude response of loop sections 1721 a,1721 b. The relatively low coupled signal between the first section 1721a of the second loop 1721 and its corresponding sensor element 1772 andbetween the second section 1721 b and its corresponding sensor element1773 generate relatively low amplitude signals on the sensor elements1772 and 1773. Each of the low amplitude signals is interpreted by thereader circuitry as representing a logical zero. When the third sensorelement 1773 is designated as representing the LSB of the code and thesecond sensor element 1772 is designated as representing the MSB of thecode, the code corresponding to the magnetic response of the loopsections 1721 a and 1721 b in the detection area 1706 is 00.

FIG. 17B illustrates a detection member 1702 comprising two spaced apartclosed conductive loops 1712, 1722. The first and second loops 1712,1722 are arranged in a detection area 1760 having three spaced apartdetection area sections 1761, 1762, 1763. The first loop 1712 isdisposed in detection area section 1761, the second loop is disposed indetection area section 1762, and no loop section is disposed indetection area section 1763. The first and second loops 1712, 1722 aregalvanically isolated and inductively coupled between the first and thesecond detection area sections 1761, 1762. A sensor array 1770comprising sensor elements 1771, 1772, 1773 is shown proximate and incommunication range of the detection member 1702.

The first sensor element 1771 is the transmit sensor in this example.The first sensor element 771 transmits an electromagnetic signal thatelectromagnetically excites the first loop 1712. The first loop 1712inductively communicates the electromagnetic energy from the transmittedsignal to the second loop 1722, generating a magnetic response in thesecond loop 1722. The second loop has a relatively high geometricalcorrespondence with respect to its sensor element 1772 resulting in arelatively high magnetic amplitude response and a relatively highamplitude signal on the sensor element 1772. The relatively highamplitude signal on sensor element 1772 represents a logical 1 in thisexample. There is no loop section disposed in detection area 1763 andthe signal on the sensor element 1773 corresponding to detection area1763 is a low or zero amplitude signal which represents a logical 0 inthis example. When the third sensor element 1773 is designated asrepresenting the LSB of the code and the second sensor element 1772 isdesignated as representing the MSB of the code, the code correspondingto the magnetic response of the loop 1722 in the detection area 1760 is10.

FIG. 17C illustrates a detection member 1703 comprising three spacedapart closed conductive loops 1713, 1723, 1733. The loops 1713, 1723,1733 are arranged in a detection area 1760 having three spaced apartdetection area sections 1761, 1762, 1763. The first loop 1713 isdisposed in detection area section 1761, the second loop 1723 isdisposed in detection area section 1762, and the third loop 1733 isdisposed in detection area section 1763. The first and second loops1713, 1723 are galvanically isolated and inductively coupled between thefirst and the second detection area sections 1761, 1762. The second andthird loops 1723, 1733 are galvanically isolated and inductively coupledbetween the second and the third detection area sections 1762, 1763. Asensor array 1770 comprising sensor elements 1771, 1772, 1773 is shownproximate and in communication range of the detection member 1703.

The first sensor element 1771 is the transmit sensor in this example.The first sensor element 1771 transmits an electromagnetic signal thatelectromagnetically excites the first loop 1713. The first loop 1713inductively communicates the electromagnetic energy from the transmittedsignal to the second loop 1723, generating a magnetic response in thesecond loop 1723. The second loop 1723 has a relatively low geometricalcorrespondence with respect to its sensor element 1772 resulting in arelatively low magnetic amplitude response and relatively low amplitudesignal on the sensor element 1772. The relatively low amplitude signalon sensor element 1772 represents a logical 0 in this example. Thesecond loop 1723 is inductively coupled to the third loop 1733 betweenthe second and third detection area sections 1762, 1763. The second loop1723 inductively communicates the electromagnetic energy from thetransmitted signal to the third loop 1733, generating a magneticresponse in the third loop 1733. The third loop 1733 has a relativelyhigh geometrical correspondence with respect to its sensor element 1773resulting in a relatively high magnetic amplitude response andrelatively high amplitude signal on the sensor element 1773. Therelatively high amplitude signal on sensor element 1773 represents alogical 1 in this example. When the third sensor element 1773 isdesignated as representing the LSB of the code and the second sensorelement 1772 is designated as representing the MSB of the code, the codecorresponding to the magnetic response of the second and third loops1723, 1733 in the detection area 1760 is 01.

FIG. 17D illustrates a detection member 1704 comprising three spacedapart closed conductive loops 1714, 1724, 1734. The loops 1714, 1724,1734 are arranged in a detection area 1760 having three spaced apartdetection area sections 1761, 1762, 1763. The first loop 1714 isdisposed in detection area section 1761, the second loop 1724 isdisposed in detection area section 1762, and the third loop 1734 isdisposed in detection area section 1763. The first and second loops1714, 1724 are galvantically isolated and inductively coupled betweenthe first and the second detection area sections 1761, 1762. The secondand third loops 1724, 1734 are galvanically isolated and inductivelycoupled between the second and the third detection area sections 1762,1763. A sensor array 1770 comprising sensor elements 1771, 1772, 1773 isshown proximate and in communication range of the detection member 1704.

The first sensor element 1771 is the transmit sensor in this example.The first sensor element 1771 transmits an electromagnetic signal thatelectromagnetically excites the first loop 1714. The first loop 1714inductively communicates the electromagnetic energy from the transmittedsignal to the second loop 1724, generating a magnetic response in thesecond loop 1724. The second loop 1724 has a relatively high geometricalcorrespondence with respect to its sensor element 1772 resulting in arelatively high magnetic amplitude response and relatively highamplitude signal on the sensor element 1772. The relatively highamplitude signal on sensor element 1772 represents a logical 1 in thisexample. The second loop 1724 is inductively coupled to the third loop1734 between the second and third detection area sections 1762, 1763.The second loop 1724 inductively communicates the electromagnetic energyfrom the transmitted signal to the third loop 1734, generating amagnetic response in the third loop 1734. The third loop 1734 also has arelatively high geometrical correspondence with respect to its sensorelement 1773 resulting in a relatively high magnetic amplitude responseand relatively amplitude signal on the sensor element 1773. Therelatively high amplitude signal on sensor element 1773 represents alogical 1 in this example. When the third sensor element 1773 isdesignated as representing the LSB of the code and the second sensorelement 1772 is designated as representing the MSB of the code, the codecorresponding to the magnetic response of the second and third loops1724, 1734 in the detection area 1760 is 11.

FIG. 17E illustrates a detection member 1705 comprising two spaced apartclosed conductive loops 1715, 1725. The loops 1715, 1725 are arranged ina detection area 1760 having three spaced apart detection area sections1761, 1762, 1763. The first loop 1715 is disposed in detection areasection 1761, a first section 1725 a of the second loop 1725 is disposedin detection area section 1762, and a second section 1725 b of thesecond loop 1725 is disposed in detection area section 1763. The firstand second loops 1715, 1725 are galvanically isolated and inductivelycoupled between the first and the second detection area sections 1761,1762. A sensor array 1770 comprising sensor elements 1771, 1772, 1773 isshown proximate and in communication range of the detection member 1705.

The first sensor element 1771 is the transmit sensor in this example.The first sensor element 1771 transmits an electromagnetic signal thatelectromagnetically excites the first loop 1715. The first loop 1715inductively communicates the electromagnetic energy from the transmittedsignal to the second loop 1725, generating magnetic responses in thespaced apart first 1725 a and second 1725 b sections of the second loop1725 The first section 1725 a of the second loop 1725 has a relativelyhigh geometrical correspondence with respect to its sensor element 1772resulting in a relatively high magnetic amplitude response andrelatively high amplitude signal on the sensor element 1772. Therelatively high amplitude signal on sensor element 1772 represents alogical 1 in this example. The second section 1725 b of the second loop1725 also has a relatively high geometrical correspondence with respectto its sensor element 1773 resulting in a relatively high magneticamplitude response and relatively high amplitude signal on the sensorelement 1773. The relatively high amplitude signal on sensor element1773 represents a logical 1 in this example. When the third sensorelement 1773 is designated as representing the LSB of the code and thesecond sensor element 1772 is designated as representing the MSB of thecode, the code corresponding to the magnetic response of the first andsecond sections 1725 a, 1725 b of the second loop 1725 in the detectionarea 1760 is 11.

A closed conductive loop and/or sections of the loop of a detectionmember may have various orientations with respect to the transmit and/orreceive sensor elements as illustrated in FIGS. 18 through 22. FIGS. 18Athrough 18D illustrate an embodiment in which a closed conductive loop1810 and sensor array 1820 are arranged along the longitudinal axis(y-axis) of a cartridge 1800. FIGS. 18A through 18D show various viewsof the cartridge 1800 that includes closed conductive loop 1810 havingsections 1811, 1812, 1813 and a sensor array 1820 comprisingcorresponding sensor elements 1821, 1822, 1823. FIG. 18A shows thecartridge 1800, closed conductive loop 1810, and sensor array 1820 whenviewed along the z axis; FIG. 18B shows the cartridge 1800, closedconductive loop 1810, and sensor array 1820 when viewed along the xaxis; and FIG. 18C shows the cartridge 1800, closed conductive loop1810, and sensor array 1820 when viewed along the y axis. FIG. 18D is anisometric view of the cartridge 1800, closed conductive loop 1810, andsensor array 1820.

The sensor elements 1821, 1822, 1823 of the sensor 1820 array are shownoriented in a plane that is substantially parallel to the planes of theloop sections 1811, 1812, 1813 in this embodiment. In this embodiment,the loop sections 1811, 1812, 1813 are disposed in two parallel planesdue to the cross over 1810 a between the first 1811 and second 1812 loopsections. When disposed longitudinally along the cylindrical cartridge1800, the loop sections 1811, 1812, 1813 and/or sensor elements 1821,1822, 1823 may not lie strictly in a flat plane due to the curvature ofthe cartridge, and thus the loop sections 1811, 1812, 1813 andcorresponding sensor elements 1821, 1822, 1823 may be disposed onparallel, curved, e.g., coaxial, surfaces.

In this embodiment, the first sensor element 1821 is the transmitelement and second and third sensor elements 1822, 1823 are receivesensor elements. The cross over 1810 a reverses the angular direction ofthe current and causes the phase of the magnetic response of the secondloop section 1812 to be shifted 180 degrees with respect to the phase ofthe magnetic response of the first loop section 1811. The phase of theelectrical signal generated on the second sensor element 1822 from thesecond loop section 1812 is phase shifted by 180 degrees with respect toan electromagnetic signal transmitted from the first sensor element1821. The phase of the magnetic response of the third loop section 1813is also shifted in phase by 180 degrees with respect to the magneticresponse of the first loop section 1811. The signal generated on thethird sensor element 1823 from the third loop section 1813 is phaseshifted by 0 degrees with respect to the signal generated on the secondsensor element 1822 from the second loop section 1812 and is phaseshifted by 180 degrees with respect to the electromagnetic signaltransmitted from the first sensor element 1821.

When the signal on the third sensor element 1823 is designated asrepresenting the LSB of the code, the signal on the second sensorelement 1822 is designated as representing the MSB of the code, and aphase shift of 180 degrees from the phase of the transmitted signalrepresents a logical 1, the code corresponding to the magnetic responseof the second and third loop sections 1812, 1813 is 11.

FIGS. 19A through 19C illustrate an embodiment in which a closedconductive loop 1910 and a sensor array 1920 are oriented along thecircumference of a cartridge 1900. FIGS. 19A through 19C show variousviews of the cartridge 1900 that includes a closed conductive loop 1910having sections 1911, 1912, 1913 and a sensor array 1920 comprisingcorresponding sensor elements 1921, 1922, 1923. FIG. 19A shows thecartridge 1900, closed conductive loop 1910, and sensor array 1920 whenviewed along the z axis; FIG. 19B shows the cartridge 1900, closedconductive loop 1910, and sensor array 1920 when viewed along the xaxis; and FIG. 19C shows the cartridge 1900, closed conductive loop1910, and sensor array 1920 when viewed along the y axis.

The loop sections 1911, 1912, 1913 of the closed conductive loop 1910and the sensor elements 1921, 1922, 1923 of the sensor array 1920 arespaced apart around a portion of the circumference of the cartridge 1900in this embodiment. When disposed circumferentially around a cylindricalhousing, the loop sections 1911, 1912, 1913 and/or sensor elements 1921,1922, 1923 may be curved such that the loop sections 1911, 1912, 1913and the corresponding sensor elements 1921, 1922, 1923 are disposed onparallel curved surfaces, e.g., coaxial surfaces.

In this embodiment, the first sensor element 1921 is the transmitelement and second and third sensor elements 1922, 1923 are receivesensor elements. The cross over 1910 a of disposed between the first1911 and second 1912 loop sections reverses the angular direction of thecurrent and causes the phase of the magnetic response of the second loopsection 1912 to be shifted 180 degrees with respect to the phase of themagnetic response of the first loop section 1911. The phase of theelectrical signal generated on the second sensor element 1922 from thesecond loop section 1912 is phase shifted by 180 degrees with respect tothe electromagnetic signal transmitted from the first sensor element1921. The phase of the magnetic response of the third loop section 1913is also shifted in phase by 180 degrees with respect to the magneticresponse of the first loop section 1911. The signal generated on thethird sensor element 1923 from the third loop section 1913 is phaseshifted by 0 degrees with respect to the signal generated on the secondsensor element 1922 from the second loop section 1912 and is phaseshifted by 180 degrees with respect to the electromagnetic signaltransmitted from the first sensor element 1921.

When the signal on the third sensor element 1923 is designated asrepresenting the LSB of the code, the signal on the second sensorelement 1922 is designated as representing the MSB of the code, and aphase shift of 180 degrees from the phase of the transmitted signalrepresents a logical 1, the code corresponding to the magnetic responseof the second and third loop sections 1912, 1913 is 11.

FIGS. 20A through 20D illustrate an embodiment in which a closedconductive loop 2010 includes a loop section 2013 that is oriented at anangle to the other loop sections 2011, 2012 and a sensor array 2020includes sensor element 2023 corresponding to loop section 2013 that isoriented at an angle to the other sensor elements 2021, 2022. FIGS. 20Athrough 20D show various views of the cartridge 2000 that includes aclosed conductive loop 2010 having sections 2011, 2012, 2013 and asensor array 2020 comprising corresponding sensor elements 2021, 2022,2023. FIG. 20A shows the cartridge 2000, closed conductive loop 2010,and sensor array 2020 when viewed along the z axis; FIG. 20B shows thecartridge 2000, closed conductive loop 2010, and sensor array 2020 whenviewed along the x axis; and FIG. 20C shows the cartridge 2000, closedconductive loop 2010, and sensor array 2020 when viewed along the yaxis. FIG. 20D is an isometric view of the cartridge 2000, closedconductive loop 2010, and sensor array 2020.

Loop sections 2011 and 2012 are spaced apart along the longitudinaly-axis of the cartridge 2000 and loop section 2013 is oriented at abouta 90 degree angle with respect to loop sections 2011 and 2012. Loopsection extends partially around the circumference of the cartridge2000. When the cartridge is cylindrical, loop sections 2011, 2012, 2013may lie in a curved plane that is parallel to the curved plane of thecartridge surface. In this embodiment, the loop sections are disposed intwo parallel surfaces due to the cross over 2010 a between the first2011 and second 2012 loop sections. Sensor elements 2021 and 2022 areoriented along the longitudinal y-axis of the cartridge 2000 and sensorelement 2023 is oriented at about a 90 degree angle with respect tosensor elements 2021 and 2022, extending around a portion of thecircumference of the cartridge 2000. When the cartridge is cylindrical,sensor elements 2021, 2022, 2023 may lie in a curved plane that isparallel and coaxial with the curved plane of the loop sections 2011,2012, 2013.

In this embodiment, the first sensor element 2021 is the transmitelement and second and third sensor elements 2022, 2023 are receivesensor elements. The cross over 2010 a of disposed between the first2011 and second 2012 loop sections reverses the angular direction of thecurrent and causes the phase of the magnetic response of the second loopsection 2012 to be shifted 180 degrees with respect to the phase of themagnetic response of the first loop section 2011. The phase of theelectrical signal generated on the second sensor element 2022 from thesecond loop section 2012 is phase shifted by 180 degrees with respect toan electromagnetic signal transmitted from the first sensor element2021. The phase of the magnetic response of the third loop section 2013is also shifted in phase by 180 degrees with respect to the magneticresponse of the first loop section 2011. The signal generated on thethird sensor element 2023 from the third loop section 2013 is phaseshifted by 0 degrees with respect to the signal generated on the secondsensor element 2022 from the second loop section 2012 and is phaseshifted by 180 degrees with respect to the electromagnetic signaltransmitted from the first sensor element 2021.

When the signal on the third sensor element 2023 is designated asrepresenting the LSB of the code, the signal on the second sensorelement 2022 is designated as representing the MSB of the code, and aphase shift of 180 degrees from the phase of the transmitted signalrepresents a logical 1, the code corresponding to the magnetic responseof the second and third loop sections 2012, 2013 is 11.

FIGS. 21A through 21C illustrate an embodiment in which the orientationof the closed conductive loop 2110 is disposed at an angle, e.g.,perpendicular, to the orientation of the sensor array 2120. FIGS. 21Athrough 21C show various views of a cartridge 2100 that includes aclosed conductive loop 2110 having sections 2111, 2112, 2113 and acorresponding sensor array 2120 comprising sensor elements 2121, 2122,2123. FIG. 21A shows the cartridge 2100, closed conductive loop 2110,and sensor array 2120 when viewed along the z axis; FIG. 21B shows thecartridge 2100, closed conductive loop 2110, and sensor array 2120 whenviewed along the x axis; and FIG. 21C shows the cartridge 2100, closedconductive loop 2110, and sensor array 2120 when viewed along the yaxis.

Closed conductive loop 2100 includes three loop sections 2111, 2112,2113 spaced apart along a longitudinal axis (y axis) of the cartridge2100. Sensor array 2120 includes three corresponding sensor elements2121, 2122, 2123 that are spaced apart along the y-axis where surfacesof the sensor elements 2121, 2122, 2123 are oriented at about a 90degree angle with respect to surfaces of their corresponding loopsections 2111, 2112, 2113.

In this embodiment, the first sensor element 2121 is the transmitelement and second and third sensor elements 2122, 2123 are receivesensor elements. The cross over 2110 a disposed between the first 2111and second 2112 loop sections reverses the angular direction of thecurrent and causes the phase of the magnetic response of the second loopsection 2112 to be shifted 180 degrees with respect to the phase of themagnetic response of the first loop section 2111. The phase of theelectrical signal generated on the second sensor element 2122 from thesecond loop section 2112 is phase shifted by 180 degrees with respect toan electromagnetic signal transmitted from the first sensor element2121. The phase of the magnetic response of the third loop section 2113is also shifted in phase by 180 degrees with respect to the magneticresponse of the first loop section 2111. The signal generated on thethird sensor element 2123 from the third loop section 2113 is phaseshifted by 0 degrees with respect to the signal generated on the secondsensor element 2122 from the second loop section 2112 and is phaseshifted by 180 degrees with respect to the electromagnetic signaltransmitted from the first sensor element 2121.

When the signal on the third sensor element 2123 is designated asrepresenting the LSB of the code, the signal on the second sensorelement 2122 is designated as representing the MSB of the code, and aphase shift of 180 degrees from the phase of the transmitted signalrepresents a logical 1, the code corresponding to the magnetic responseof the second and third loop sections 2112, 2113 is 11.

FIGS. 22A through 22C illustrate an embodiment in which a closedconductive loop 2210 and sensor array 2220 are spaced apart along thelongitudinal axis of the cartridge 2200. The second section 2212 of theclosed conductive loop 2210 is rotated along the longitudinal axis(y-axis) of the cartridge 2200 with respect to the first 2211 and third2213 sections of the closed conductive loop 2210. The second sensor 2222is rotated along the longitudinal axis (y-axis) of the cartridge 2200with respect to the first 2221 and third 2223 sensor elements. FIGS. 22Athrough 22C show various views of a cartridge 2200 that includes aclosed conductive loop 2210 having sections 2211, 2212, 2213 and asensor array 2220 comprising corresponding sensor elements 2221, 2222,2223. FIG. 22A shows the cartridge 2200, closed conductive loop 2210,and sensor array 2220 when viewed along the z axis; FIG. 22B shows thecartridge 2200, closed conductive loop 2210, and sensor array 2220 whenviewed along the x axis; and FIG. 22C shows the cartridge 2200, closedconductive loop 2210, and sensor array 2220 when viewed along the yaxis.

The loop 2210 includes two cross overs 2210 a, 2210 b and the loop 2210is rotated 180 degrees along its length around the y-axis. The surfaceof the second loop section 2212 is rotated 90 degrees with respect tothe orientation of the surface of the first loop section 2211. Thesurface of the third loop section 2213 is rotated 90 degrees withrespect to the orientation of the surface of the second loop section2212 and is rotated 180 degrees with respect to the orientation of thesurface of the first loop sections 2211.

Sensor array 2220 includes three sensor elements 2221, 2222, 2223 thatare spaced apart along the y-axis. The surface of the first sensorelement 2221 is substantially parallel to the surface of the first loopsection 2211. The surface of the second sensor element 2222 issubstantially perpendicular to the surface of the second loop section2212. The surface of the third sensor element 2223 is substantiallyparallel to the surface of the third loop section 2213.

In this embodiment, the first sensor element 2221 is the transmitelement and second and third sensor elements 2222, 2223 are receivesensor elements. The first cross over 2210 a causes the phase of themagnetic response of the second loop section 2212 to be shifted 180degrees with respect to the phase of the magnetic response of the firstloop section 2211. The phase of the electrical signal induced on thesecond sensor element 2222 by the second loop section 2212 is phaseshifted by 180 degrees with respect to an electromagnetic signaltransmitted from the first sensor element 2221. The phase of theelectrical signal generated on the third sensor element 2223 by thethird loop section 2213 is phase shifted by 180 degrees with respect tothe signal generated on the second sensor element 2222 and is phaseshifted by 360 (0) degrees with respect to the electromagnetic signaltransmitted from the first sensor element 2221. The substantiallyperpendicular orientation between the sensor element 2222 and secondloop section 2212 results in a smaller induced signal amplitude onsensor 2222 by the second loop section 2212 than the signal amplitude onsensor element 2223 caused by the third loop section 2213. Thesubstantially parallel orientation between the sensor element 2223 andsecond loop section 2213 results in a larger induced signal amplitude onsensor 2223 by the second loop section 2213 than the signal amplitude onsensor element 2222 caused by the third loop section 2212.

When the signal on the third sensor element 2223 is designated asrepresenting the LSB of the code, the signal on the second sensorelement 2222 is designated as representing the MSB of the code, and aphase shift of 180 degrees from the transmitted signal represents alogical 1, the code corresponding to the magnetic response of the secondand third loop sections 2212, 2213 is 10. Alternatively, when the thirdsensor element 2223 is designated as representing the LSB of the codeand the second sensor element 2222 is designated as representing the MSBof the code, and a high amplitude signal interpreted as a logical 1 anda low amplitude signal interpreted as a logical 0, the codecorresponding to the loop sections 2212, 2213 of loop 2210 is 01.

FIGS. 23 through 26 are flow diagrams that illustrate the operation of adetection system according to some embodiments. FIG. 23 provides a highlevel diagram of system operation. After power on 2310 of the system,the microcontroller of the reader optionally fetches 2320 the baselinecalibration authentication information, if available. In someimplementations, the detection system may operate without baselinecalibration authentication information. Authentication measurements 2330are taken by transmitting electromagnetic signals from one or moresensor elements and sensing the magnetic responses of one or more loopsections using one or more sensor elements. The authenticationmeasurements are compared 2340 to the baseline information to determinethe logic levels of the sensed magnetic responses. The reader determines2350 if the code read from the detection member is authentic and reportsthe results, e.g., via a user interface. The system may sleep 2360 for aperiod of time and initiate additional authentication measurement cyclesat predetermined intervals or upon request.

FIG. 24 illustrates how the reader's baseline calibration is performedin accordance with some embodiments. After system power on 2405, themicrocontroller of the reader checks 2410 if a valid authentication keyhas been set indicating that a baseline calibration has previously beenperformed. If the valid authentication key has been set, the controllermoves 2445 the baseline data from non-volatile memory to random accessmemory (RAM) and concludes 2450 the baseline calibration.

If the valid authentication key has not been set 2410, the reader beginsthe process of locating the resonant frequencies of the sensor elements.The reader transmits an electromagnetic signal from one of the sensorelements, referred to as the transmitter element, sweeping 2415 througha relatively wide band of frequencies, e.g., 10-30 MHz, while sensingthe response of the other sensor elements. If initial resonant signalpeaks are detected 2420 from the other (non-transmitting) sensorelements, the reader computes 2425 a narrower sweep band of frequenciesthat corresponds to the detected initial resonant peaks and performs asecond sweep through the narrower band of frequencies. After using thewider band sweep to determine approximate resonant frequencies thereader will compute the settings to achieve a narrower band sweep. Itwill then utilize these settings in order to sweep over 2425 thenarrower band and make the appropriate baseline measurements for eachcombination of sensor elements used as the transmitting elements.

If resonant peaks are detected 2430 during the second sweep, the readercircuitry calculates 2435 the new resonant frequencies and the baselineamplitudes of the sensor elements at the resonant frequencies. Theresonant frequencies and baseline amplitudes for each loop section arestored 2440 in non-volatile memory and sets the authentication validkey. The reader circuitry may make several attempts to locate theresonant frequencies by performing the wider band sweep and the narrowerband sweep a predetermined number of times. If no resonant frequenciesare located 2420, 2430 after performing one or both of the wider andnarrower band sweeps the predetermined number of times, the readercircuitry indicates 2455 a hardware failure.

FIG. 25 is a flow diagram illustrating a process of sensing the magneticresponse of conductive loop sections and determining the code of theconductive loop in accordance with some embodiments. In this embodiment,the conductive loop includes three loop sections which are designated asleft, right, and middle. The left, right, and middle loop sectionscorrespond to left, right, and middle sensor elements.

On startup the calibration information is loaded if it is deemed valid.If not valid, which would be the case the first time the electronics arepowered up, then baseline amplitude and resonant frequency informationwould be captured and stored into non-volatile memory and thecalibration would then be identified as being valid. On any subsequentstartup the stored calibration information would be used to determineauthenticity. Authentication measurements taken outside of calibrationare only stored in volatile memory and utilized to make the decisionregarding authenticity. Initially, the baseline measurements and sweepparameters, e.g., sweep band, corresponding to each drive andmeasurement configuration used are loaded 2505, 2510, if these baselinemeasurements are available. The system proceeds to transmit and senseusing various optional sensor element combinations. For example, thesystem may drive the right and left sensor elements with electromagneticsignals that are in phase and sense 2515 the magnetic response from theleft section of the conductive loop using the left sensor element; thesystem may drive the right and left sensor elements with electromagneticsignals that are in phase and sense 2520 the magnetic response from theright section of the conductive loop using the right sensor element; thesystem may drive the right sensor element only and sense 2525 themagnetic response from the middle section of the conductive loop usingthe middle sensor element; the system may drive the right sensor elementonly and sense 2530 the left section of the conductive loop using theleft sensor element; the system may drive the right and left sensorelements in phase and sense 2535 the magnetic response of the middlesection of the conductive loop using the middle sensor element; and/orthe system may drive the right and left sensor elements out of phase,e.g., 180 degrees out of phase and sense 2540 the magnetic response ofthe middle section of the conductive loop using the middle sensorelement. The system stores 2550 the sensed amplitude and calculatedresonant frequency for each of the measurements and sends 2555 thestored amplitudes and resonant frequencies to the authenticationmanager.

FIG. 26 is a flow diagram illustrating an authentication process inaccordance with some embodiments. Prior to the process of FIG. 26, abaseline calibration may have been performed, e.g., by the processoutlined in FIG. 24 and the magnetic responses of the loop sections havemeasured, e.g., by the process outlined in FIG. 25. In this embodiment,the conductive loop can represent four different codes. The readercircuitry fetches 2605 the baseline information and the recentmeasurements of the magnetic responses of the loop sections. The readercircuitry compares 2610-2625 the recent measurements to each possiblecode, indicated as Tag A, Tag B, Tag C, Tag D in FIG. 26. If the recentmeasurements correspond to one of the possible codes, then the treatmentcartridge is authenticated 2630. The reader may report this status toother circuitry and/or provide an indication via a user interface thatthe cartridge is authenticated.

If the recent measurements do not correspond to any of the possiblecodes, the reader circuitry may check 2635, if a treatment cartridge ispresent. If no treatment cartridge is present 2645, the reader mayreport this status to other circuitry and/or provide an indication via auser interface that no cartridge is present. If a treatment cartridge ispresent, then the conductive loop and/or treatment cartridge are notauthenticated 2640. The reader may report this status to other circuitryand/or provide an indication via a user interface that the cartridgecannot be authenticated.

EXAMPLES

Various three section conductive loop configurations were constructedand tested with different drive arrangements. In the following examples,the three loop sections are referred to as the leftmost, center, andrightmost loop sections. The corresponding sensor elements of the readerare referred to as leftmost, center, and rightmost sensor elements. In asingle drive arrangement, a rightmost sensor element energizes therightmost section of the conductive loop, the center sensor elementsenses the magnetic response of the center section of the conductiveloop, and the leftmost sensor element senses the magnetic response ofthe leftmost section of the conductive loop. In a dual drive in-phasearrangement, rightmost and leftmost sensor elements transmitelectromagnetic signals that are in-phase with each other and thatrespectively energize the rightmost section and the leftmost section ofthe conductive loop. The center sensor element senses a magneticresponse of the center section of the conductive loop. In a dual driveout-of-phase arrangement, rightmost and leftmost sensor elementstransmit electromagnetic signals that are out-of-phase with each otherand that respectively energize the rightmost section and the leftmostsection of the conductive loop. The center sensor element senses themagnetic response of the center section of the conductive loop.

Example 1

FIGS. 27A-27C compare graphs of the baseline and measurement signals fora simple conductive loop having the configuration generally shown inFIG. 1B and having three sections. FIG. 27A shows the baseline andmeasurement signals on the center and leftmost sensor elements when asingle energizing signal is transmitted from the rightmost sensorelement. Increased coupling between the center and rightmost sensorelements due to their proximity to each other increases the amplitudesof the baseline and measurement signals of the center sensor elementrelative to the amplitudes of the baseline and measurement signals ofthe leftmost sensor element.

FIG. 27B shows the baseline and measurement signals on the center sensorelement when the leftmost and rightmost sensor elements transmit dualenergizing signals that are in phase. The response of the center antennahas a much higher amplitude because the loop in enhancing the amount ofmagnetic coupling to the center sensor element. FIG. 27C shows thebaseline and measurement signals on the center sensor element when theleftmost and rightmost sensor elements transmit dual energizing signalsthat are out-of-phase. As shown in FIG. 27C, although the measurementsignal has a much smaller amplitude when compared with the measurementsignals of FIGS. 27A and 27B, it is still distinguishable from thebaseline signal.

Example 2

FIGS. 28A-28C compare graphs of the baseline and measurement signals fora conductive loop having the configuration generally shown in FIG. 9Awith three sections. In this example, the center section has notches ateither side of the center loop section that increase the geometricalsimilarity between the center loop section and its corresponding centersensor element. FIG. 28A shows the baseline and measurement signals onthe center and leftmost sensor elements when a single energizing signalis transmitted from the rightmost sensor element. FIG. 28B shows thebaseline and measurement signals on the center sensor element when theleftmost and rightmost sensor elements transmit dual energizing signalsthat are in phase. FIG. 28C shows the baseline and measurement signalson the center sensor element when the leftmost and rightmost sensorelements transmit dual energizing signals that are out-of-phase. Asshown in FIG. 28C, although the measurement signal has a much smalleramplitude when compared with the measurement signals of FIGS. 28A and28B, it is distinguishable from the baseline signal. The increasedgeometrical similarity between the center loop section and the centersensor element in this example increases the measurement signals on thecenter sensor element when compared to the measurement signals of thecenter sensor element for the simple loop example shown in FIGS.27A-27C. The geometrical similarity of all of the loops has beenincreased in this example and for this reason the comparison betweenFIGS. 27A and 28A shows an increase in amplitude for both the center andleftmost sensor elements by approximately 150 and 100 respectively. Thesame similarity exists when comparing FIG. 27B and FIG. 28B showing anincrease in amplitude of approximately the sum of the single drivevalues or approximately 250.

Example 3

FIGS. 29A-29C compare graphs of the baseline and measurement signals fora conductive loop with the configuration generally shown in FIG. 7A andhaving three sections with a notch extends across the center loopsection, reducing the coupling between the center loop section and thecorresponding center sensor element. FIG. 29A shows the baseline andmeasurement signals on the center and leftmost sensor elements when asingle energizing signal is transmitted from the rightmost sensorelement. The leftmost sensor had a higher amplitude increase relative tothe leftmost sensor baseline signal compared to the signal amplitudeincrease of the center sensor relative to the center sensor baselinesignal.

FIG. 29B shows the baseline and measurement signals on the center sensorelement when the leftmost and rightmost sensor elements transmit dualenergizing signals that are in phase. FIG. 29C shows the baseline andmeasurement signals on the center sensor element when the leftmost andrightmost sensor elements transmit dual energizing signals that areout-of-phase. The decreased coupling between the center loop section andthe center sensor element results in small, but measurable, amplitudechanges of the measurement signals of the center sensor relative to theamplitude of the baseline signals of the center sensor.

Since the leftmost sensor element responds in amplitude and the centersensor element amplitude stays similar to the baseline means a tag withand extended notch or patch of metal has been used to create thissignal. The frequency increase for the center sensor element gives someindication that metal has been placed in front of the sensing element.However, the shift is minor so it is not a complete patch of metal,which leads to the determination that this is an extended notch tag.

Example 4

FIGS. 30A-30C compare graphs of the baseline and measurement signals fora conductive loop having the configuration generally shown in FIG. 8Aand having three sections with two loop branches that extend across thecenter loop section. The loop branches reduce the coupling between thecenter loop section and the corresponding center sensor element comparedto the coupling of Example 1. FIG. 30A shows the baseline andmeasurement signals on the center and leftmost sensor elements when asingle energizing signal is transmitted from the rightmost sensorelement.

FIG. 30B shows the baseline and measurement signals on the center sensorelement when the leftmost and rightmost sensor elements transmit dualenergizing signals that are in phase. FIG. 30C shows the baseline andmeasurement signals on the center sensor element when the leftmost andrightmost sensor elements transmit dual energizing signals that areout-of-phase. The decreased coupling between the center loop section andthe center sensor element reduces the amplitude changes of themeasurement signals of the center sensor relative to the amplitude ofthe baseline signals of the center sensor relative to the amplitudechanges of Example 1.

For the example of FIGS. 30A-30C the design has similar coupling betweenthe left and right sensor elements as the Example shown in FIG. 29A withthe extended notch. However the center element has more than theextended notch. This mid-level center coupling along with a moresignificant frequency shift is a distinguishing feature that there aredual loops.

Example 5

FIGS. 31A-31C compare graphs of the baseline and measurement signals fora conductive loop having the configuration generally shown in FIG. 11and having three sections. A conductive peninsula extends across thecenter loop section, masking the amplitude response of the center loopsection. FIG. 31A shows the baseline and measurement signals on thecenter and leftmost sensor elements when a single energizing signal istransmitted from the rightmost sensor element. FIG. 31B shows thebaseline and measurement signals on the center sensor element when theleftmost and rightmost sensor elements transmit dual energizing signalsthat are in phase. FIG. 31C shows the baseline and measurement signalson the center sensor element when the leftmost and rightmost sensorelements transmit dual energizing signals that are out-of-phase.

In this example, the conductive peninsula of the center loop sectioncauses a smaller amplitude change of the center sensor compared to thebaseline of the center sensor relative to the amplitude change of theleftmost sensor relative to the baseline of the leftmost sensor. Inaddition, the conductive peninsula shifts the frequency having themaximum amplitude on the measured signal of the center sensor highercompared to the baseline of the center sensor. The conductive peninsulacauses a significant frequency shift to occur on the center sensorelement while keeping the coupling to be nearly unchanged from thebaseline.

Example 6

FIGS. 32A-32C compare graphs of the baseline and measurement signals fora conductive loop having the configuration generally shown in FIG. 12and having three sections. A conductive island extends across the centerloop section, modifying the amplitude response of the center loopsection. FIG. 32A shows the baseline and measurement signals on thecenter and leftmost sensor elements when a single energizing signal istransmitted from the rightmost sensor element. FIG. 32B shows thebaseline and measurement signals on the center sensor element when theleftmost and rightmost sensor elements transmit dual energizing signalsthat are in phase. FIG. 32C shows the baseline and measurement signalson the center sensor element when the leftmost and rightmost sensorelements transmit dual energizing signals that are out-of-phase. Thesegraphs show a similar, but moderately smaller, change in the signalamplitudes compared the graphs of Example 1. Compared to Example 1, theshift of the frequency at maximum amplitude is larger for the centermeasured signal relative to the baseline signal.

In this example, the conductive island decreases the amplitude slightlywhen compared to a loop with no island. Additionally, the conductiveisland causes the frequency to shift by approximately the same amount asthe peninsula feature shown in FIG. 31. In this example, the amplituderesponse of the center sensor element is distinguishably greater thanthe amplitude response of the center sensor element of the dual loopfeature.

Example 7

FIGS. 33A-33C compare graphs of the baseline and measurement signals fora conductive loop having the configuration generally shown in FIG. 6Aand having three sections with a cross over between the leftmost andcenter loop sections. FIG. 33A shows the baseline and measurementsignals on the center and leftmost sensor elements when a singleenergizing signal is transmitted from the rightmost sensor element. FIG.33B shows the baseline and measurement signals on the center sensorelement when the leftmost and rightmost sensor elements transmit dualenergizing signals that are in phase. The cross over causes the measuredsignal amplitude on the center sensor to be lower than the baseline.FIG. 33C shows the baseline and measurement signals on the center sensorelement when the leftmost and rightmost sensor elements transmit dualenergizing signals that are out-of-phase.

With respect to the transmitted signal for a single drive configuration,the phase of the received signal on the center sensor element is inphase with respect to the transmitted signal and the leftmost sensorelement is 180 degrees out of phase. For dual drive and in phase theresulting phase on the center sensor element is the same as thetransmitted signal but the net current in the loop is minimal as bothtransmitters are close to offsetting each other. For dual drive out ofphase the resulting phase on the center sensor element is in phase withrespect to the rightmost (original single drive) transmitter element. Ifthe crossover were moved to be between the rightmost and the center thenthe resulting phase for this would be 180 degrees out of phase withrespect to the rightmost transmit signal.

Example 8

FIGS. 34A-34C compare graphs of the baseline and measurement signals fora conductive loop having the configuration generally shown in FIG. 6Aand having three sections with a first cross over between the rightmostloop section and the center loop section and a second cross over betweenthe center loop section and the leftmost loop section. FIG. 34A showsthe baseline and measurement signals on the center and leftmost sensorelements when a single energizing signal is transmitted from therightmost sensor element. FIG. 34B shows the baseline and measurementsignals on the center sensor element when the leftmost and rightmostsensor elements transmit dual energizing signals that are in phase. FIG.34C shows the baseline and measurement signals on the center sensorelement when the leftmost and rightmost sensor elements transmit dualenergizing signals that are out-of-phase.

For the single transmitter sensor element situation case, the receivedphase of the center is 180 degrees out of phase with respect to thetransmitted signal. However, the leftmost sensor element is in phasewith the transmitted signal. For the dual drive in phase the resultingsignal on the center sensor element is 180 out of phase with respect tothe transmitted signal. The dual drive out of phase situation wouldideally be a net zero coupling for the two transmitters. However,practically one of the two transmitters will end up with minimallyhigher coupling and be the deciding phase value

Parameters associated with the capacity of a treatment media can bemonitored by detecting properties of an electromagnetic signal thatinteracts with the treatment media. In some embodiments, a reader thatreads the code of a closed conductive loop of a treatment cartridge asdescribed above and a capacity sensor that senses parameters related tothe capacity of the treatment media of the treatment cartridge mayoperate as separate entities with separate components. Additionaldetails regarding capacity monitoring sensors for treatment media andcapacity monitoring systems are described in commonly owned U.S. PatentApplication Ser. 62/205,481, U.S. Patent Application Ser. 62/205,502,and U.S. Patent Application Ser. 62/205,517, each of which was filed onAug. 14, 2015 and is incorporated herein by reference. Additionaldetails regarding capacity monitoring sensors for treatment media andcapacity monitoring systems are described in commonly owned U.S. PatentApplication Ser. 62/263,431, U.S. Patent Application Ser. 62/263,439,and U.S. Patent Application Ser. 62/263,441, each of which was filed onDec. 4, 2015 and is incorporated herein by reference.

In other embodiments, the reader described above and a capacity sensormay share at least some components. For example, one or more of thesensor elements of the reader may provide and/or sense anelectromagnetic field for monitoring the capacity of treatment media.Additionally, or alternatively, the reader circuitry, e.g., transceiversand/or a controller may provide functionality for the capacity sensor.For example, in a first mode, one or more of the sensor elements and thereader circuity may operate to detect the presence of the cartridge andto read the code of the detection member to detect, authenticate,classify, and/or identify the treatment cartridge as described above. Ina second mode, one or more of the sensor elements and/or the readercircuitry may operate as part of a capacity sensor that detects and/ormonitors over time one or more parameters of treatment media.

A combined reader/capacity sensor associated with a treatment cartridgecan be configured to detect, authenticate, classify and/or identify thetreatment cartridge based on the code of the detection member. Forexample, the reader may detect the presence of a treatment cartridgeincluding verifying proper insertion of the cartridge. The reader maydetermine the type cartridge based on the code of the detection member.The reader may authenticate that the type of cartridge is compatiblewith the host system in which it is installed based on the code and/orinformation stored in the reader circuitry. In some implementations, thecode of the detection member may be an identification code and readermay identify the cartridge based on the code. The reader may classifythe cartridge based on the detected code, including classifying thetreatment cartridge with regard to the designed maximum volume to betreated, flow rate, pressure drop, treatment media type, housing type,etc. The identification and/or classification of the treatment cartridgeand/or treatment media within the cartridge can assist in ensuringproper configuration of the filtration and improvement of the filtrationprocess. The identification and/or classification of the treatmentcartridge and/or treatment media may also facilitate accurate capacitymonitoring of the treatment media.

The reader/capacity sensor generates an electromagnetic field foractively monitoring the capacity of a treatment media contained withinthe housing. For example, the reader/capacity sensor may produce amagnetic field that propagates through the nonconductive treatmenthousing into the treatment media and is sensed by field sensor of thereader/capacity sensor.

In some embodiments the circuitry of the reader/capacity sensordetermines the remaining capacity of the treatment media by periodicallygenerating an incident magnetic field into the treatment media andmeasuring any change in one or more properties of the magnetic fieldcaused by the changes in one or more characteristics (e.g.,conductivity, dielectric strength, magnetic permeability, or the like)of the treatment media over time as fluid flows through the treatmentmedia. In general, treatment capacity or efficacy refers to theremaining capability of the treatment media to remove filtrate from theuntreated fluid. The term remaining treatment capacity or currentcapacity may be used to express the treatment capacity at a point intime or at the time of a measurement. Treatment capacity may beexpressed in volume, time, percent of initial, mass, or number ofparticles or other units.

Moreover, in addition (or in the alternative) to directly measuringtreatment capacity by monitoring the conductivity, dielectric, orpermeability change of the treatment media, the treatment capacity canalso be determined by measuring the change in conductivity, dielectric,or permeability of a surrogate material connected to the same fluidflow. The treatment capacity can then be calculated based on a knownrelationship by a measured conductivity, dielectric, or permeabilitychange of the surrogate material and the conductivity, dielectric, orpermeability change of the treatment media. The surrogate material cancomprise of the same treatment media, different treatment media,non-treatment media material, or any combination and could have adifferent form factor. One or more surrogate materials can be connectedin series or in parallel. The surrogate material could provide afiltration function or no filtration function. Several advantages ofutilizing a surrogate material could be a surrogate material has ahigher sensitivity, lower sensitivity, enables a simpler system,improved stability, and is reusable.

FIG. 35A is a block diagram of a reader/capacity sensor 3501 havingshared circuitry and separate capacity sensing and closed loop codereading sensor components in accordance with some embodiments. FIG. 35Bis a block diagram that illustrates a reader/capacity sensor 3502 havingshared reader/capacity sensing circuitry and wherein the antenna andfield sensor for capacity sensing are also used as sensor elements forthe closed loop code reader. In other embodiments, the antenna of thecapacity sensor is a separate from the code reader sensor elements andthe capacity sensing field sensor is also serves as a code readingsensor element. In other embodiments, the field sensor of the capacitysensor is a separate from the code reader sensor elements and thecapacity sensing antenna also serves as a code reading sensor element.Additionally, in some embodiments, components of the code reader sensorelements, capacity sensing antenna, and capacity sensing field sensormay be shared while the circuitry coupled to these elements is separate.

FIG. 35A is a block diagram of a reader/capacity sensor 3501 inaccordance with some embodiments. The reader/capacity sensor 3501includes reader/capacity sensor circuitry 3505, a capacity sensingantenna 3563, a capacity sensing field sensor 3564, and closed loop codesensor elements 3565 a-d. In this implementation, the sensor elements3565 a-d that detect the code of the closed conductive loop 3550 areseparate from the antenna 3563 and field sensor 3564 used to detect thecapacity of the treatment media. The reader/capacity sensor 3501 isshown next to a treatment cartridge 3570. The housing 3572 of thetreatment cartridge 3570 is non-conductive, e.g., plastic, glass,porcelain, rubber, and contains treatment media 3571 for the filtrationof liquids or gases.

The capacity sensor antenna 3563, capacity sensor field sensor 3564 andthe sensor elements 3565 a-d of the reader/capacity sensor areelectrically coupled to transceiver circuitry 3510 of thereader/capacity sensor. For capacity sensing, an internal power source3530, such as a battery, and transceiver 3510 of reader/capacity sensorgenerate an alternating electrical current, e.g., RF signal, through theantenna 3563 so as to produce an electromagnetic field within thetreatment media. In general, the electromagnetic field propagatesthrough at least a portion of the treatment media 3571 contained withintreatment housing 3570. Examples of a suitable antenna 3563 for capacitysensing include a single turn inductor, a multi-turn inductor, atwo-dimensional conductive loop, a conductive loop with threedimensional features, and a capacitive element. The antenna 3563 may benon-resonant, resonant, or self-resonant. Examples of controller 3520include an embedded microcontroller, an Application Specific IntegratedCircuit (ASIC), a field programmable gate array (FPGA), a digital signalprocessor (DSP), a general purposes embedded microprocessor, a logicgate, or the like, or combinations thereof.

Responsive to commands from controller 3520, the transceiver 3510 may,for example, generate an RF signal as one or more sinusoidal waves, asquare wave, a discontinuous signal or the like. Transceiver 3510 may,as described herein, control a shape, phase, e.g., phase shift, and/oran amplitude of the electromagnetic signal.

As described herein, the treatment media 3571 within housing 3570interacts with the electromagnetic field produced by the antenna 3563.For example, the electromagnetic field may interact with the treatmentmedia to induce eddy currents within the treatment media 3571. Creationof the field eddy currents in turn operate to reduce a strength of theelectromagnetic field produced by the antenna 3563. The field sensor3564 and controller 3520 monitor characteristics of the electromagneticfield produced by the antenna 3563, and, based on those characteristics,the controller 3520 determines qualities (strength, amplitude, phase,etc.) of the electromagnetic field that are associated with propertiesof the antenna 3563. The controller 3520 may determine properties of theantenna 3563 that are related to interaction between the treatment mediaand the electromagnetic field. Example properties of the antenna 3563that may be influenced by the interaction between the treatment mediaand the electromagnetic field so as to be detected by the field sensor3564 and controller 3520 include inductance, capacitance, reactance,impedance, equivalent series resistance, equivalent parallel resistance,quality factor, and resonant frequency of the antenna 3563.

By monitoring changes in certain qualities of the electromagnetic fieldthat are related to properties of the antenna 3563 and are influenced bythe interaction between the treatment media 3571 and the electromagneticfield, the controller 3520 detects changes in characteristics of thecontained treatment media that relate to treatment media capacity. Thematerial property of the treatment media may be, for example, electricalconductivity, magnetic permeability, magnetic loss tangent, magneticcoercivity, magnetic saturation, dielectric constant, dielectric losstangent, or dielectric strength of the treatment media.

In some example implementations controller 3520 is configured to directtransceiver 3510 to sweep the excitation frequency of antenna 3563 tomeasure the frequency response of the antenna. The frequency sweep maybe executed as controllable discrete linear steps, log steps, or other.The size of the steps is one factor in determining sensor frequencyresolution and measurement refresh rate. For a 1 MHz sweep range with 1KHz linear steps and each step consuming 100 us, the total sweep timewould be 1000*100 us=100 ms. For the same system with 10 kHz steps, thetotal sweep time would be 100*100 us=10 ms. The decreased sweep timewith 10 kHz steps will decrease the frequency resolution of themeasurement. In some examples, signal processing methods such asinterpolation and regression may be used to increase the frequencyresolution of the measurement.

In some applications, the measured signal may be small resulting in anoisy measurement. One method to increase the signal strength is tocontrol the amplitude of the generated signal. In one example, theamplitude of signal is increased to fully utilize the dynamic range ofthe detection circuit.

In one example, the quality-factor of a resonant antenna can bemonitored by a ring-down method. This method includes exciting theresonant antenna, removing the excitation source, and measuring thesignal of the resonant antenna as the signal decays. The decay rate isinversely proportional to the quality factor. In this example,controlling or having knowledge of the phase, may allow the excitationto be terminated at zero-current and minimize switching spikes caused bythe excitation.

In the example of FIG. 35A, transceiver 3510 interfaces with a fieldsensor 3564, e.g., receiving antenna, to measure properties of theelectromagnetic field generated by antenna 3563. In one example, fieldsensor 3564 is an inductance-to-digital converter that operates inclosed-loop fashion with transceiver 3510 to monitor the energydissipated by antenna 3563 and output a digital value indicative of amagnitude of the electromagnetic field currently being produced by theantenna 3563. The field sensor 3564 may output one or more signalsindicative of a variety of properties of antenna 3563 when being drivento create the electromagnetic field, such as inductance, capacitance,resonant frequency, quality factor, equivalent series resistance, orequivalent parallel resistance. In some examples, field sensor 3564 andtransceiver 3510 may be implemented in a common integrated circuit orcomponent, such as an LDC1000 available from Texas Instruments™ ofDallas, Tex. Based on the output of field sensor 2464 and transceiver3510 as described herein, controller 3520 computes parameters indicativeof characteristics of the conductivity, dielectric strength, magneticpermeability, or the like of treatment media 3571.

The controller 3520 operates user interface 3540 to display or transmitindicators representative of treatment media 3571 conductivity,dielectric strength, magnetic permeability, or the like. In someexamples, user interface 3540 may include, for example, a plurality oflights such as, for example, light emitting diodes, incandescent bulbs,or the like. In other examples, user interface may include, for example,a graphical interface, a touch screen, or the like. In some examples,the indicator lights correspond to the lifetime or capacity of thetreatment media based upon the treatment media 3571 conductivity,dielectric strength, magnetic permeability, or the like. In someexamples, user interface 3540 may be configured to transmit signals viaa radio transmitter. In some examples, the radio transmitter signalsinclude the determined characteristics of treatment media 3571, such asremaining capacity, by radio frequency communication, wireless localarea network (WLAN) connection, or the like. In other examples, userinterface 3540 may transmit raw treatment media data, such asconductivity, dielectric strength, magnetic permeability, or the likefor remote analysis.

In one example, the controller 3520 comprises of at least one of thefollowing components: read-only memory (ROM), random-access memory(RAM), processor, analog peripheral, and digital peripheral. In someinstances, the controller may be an integrated circuit (IC), such as anapplication specific integrated circuit (ASIC), field programmable logicarray (FPGA), embedded microcontroller, embedded microprocessor, orlogic gate. In other instances, the controller can be an amalgamation ofseveral circuits or several integrated circuits interacting togetherwith inputs and outputs. This controller utilizes its components to formdecisions and measurements of the present treatment capacity. Thesedecisions can be made via signal processing techniques, algorithms,and/or data management. Measurements can be either analog measurementsfrom at least one analog to digital converter (ADC), digitalmeasurements from at least one digital interface, or wirelessmeasurement from at least one wireless interface.

In some instances, the controller 3520 provides provide feedback to theuser regarding the state of the treatment media 3571. One feedbackmechanism is digital communication. This form of communication could bebut is not limited to unidirectional or bidirectional data flow betweenthe controller 3520 and an external entity that is capable of thedigital communication. An example of unidirectional digitalcommunication is universal asynchronous receiver/transmitter (UART),where only one data line connects the controller of the sensor toexternal entity capable of receiving UART communication. A few examplesof bidirectional digital communication from the controller of the sensorcould be serial peripheral interface (SPI), inter-integrated circuit(I2C), or UART communication. The digital communication can pass datafrom the sensor controller by sending raw measurement data or processedinformation. There are advantages to both data exchanges, as refinedinformation can be sent more quickly, whereas raw measurement data canbe sent to another entity for processing.

In some instances, the controller 3520 provides feedback to an entitythat does not accept digital or wireless communication. One of suchother feedback mechanisms is through analog communication. This form ofcommunication may be but is not limited to at least one digital toanalog converter (DAC) output. In some instances, using an analog outputcan be easier and simpler to transfer data or information from thesensor controller. When a DAC output is synchronized by a time base forperiodic sampling intervals, one can transfer data as an analog signal.Analog signals may be but are not limited to sinusoids, square waves,triangle waves, saw tooth waves, and direct current (DC) level signals.

In some examples, a wired connection is not desired or possible forcommunication. In such instances, a wireless communication network canbe implemented. A wireless communication network may include at leastone sensor controller, and can be interfaced to a user interface (UI)entity, other processing entity, or other sensor controller. This formof communication may be but is not limited to at least one Wi-Finetwork, Bluetooth connection, or ZigBee network. Communication can beunidirectional or bidirectional. The hardware of the communication maymodulate the data transfer in a particular scheme such as frequencyshift keying (FSK). When the controller needs to release data orinformation, it can send it over a wireless channel to another entityfor read out or processing.

In many instances, the reader/capacity sensor is configured to alert oralarm the user. Such events, such as the present treatment capacityreaching a certain threshold, may be communicated to the user throughvisible, audible, or physical methods. Such examples of an alert systeminclude but are not limited to a DAC output, a function generator, adisplay, a speaker, a buzzer, or a haptic feedback mechanism. These userinterfaces can be in communication with the sensor controller viaanalog, digital, or wireless communication.

In general, the forms of communication described above (digital, analog,and wireless), typically utilize a time based protocol generated by atleast one timer circuit in the controller to maintain proper timingbetween data transfer sampling or signal clocking. A timer circuit couldbe a software timer inside of the controller, an analog circuit withtime constants from charging/discharging, a software- orhardware-defined counter, or a clock signal from a communicationchannel. The time based protocol may also allow for the periodicsampling of the sensor to obtain measurements regarding the treatmentmedia.

FIG. 35B depicts a reader/capacity sensor 3502 in which the sensorelements of the reader 3565 a-d also serve as the antenna and fieldsensor for capacity sensing. In this embodiment, the reader/capacitysensor 3502, comprising sensor elements 3565 a-d and reader circuitry3505 read the code of the detection member 3550, e.g., at the time ofinstallation of the cartridge. After the code has been read by thereader/capacity sensor, at least a first sensor element is used as theantenna of the capacity sensor and at least another second sensorelement is used as the field sensor of the capacity sensor.

FIGS. 36A and 36B are a diagrams illustrating in further detail oneexample implementation of a reader/capacity sensor 3620 coupled to anexample treatment housing 3621. In this embodiment the antenna of thecapacity sensing portion of the reader/capacity sensor 3620 encirclesthe treatment housing 3621. The reader/capacity sensor 3620 includes oneor more sensor elements 3631 a, 3631 b, 3631 c, 3631 d configured toread the code of a detection member (not shown) of the treatment housing3621. In some embodiments, the reader/capacity sensor 3620 may include afield sensor for capacity sensing that is separate from the sensorelements 3631 a, 3631 b, 3631 c, 3631 d. In some embodiments, one ormore of the sensor elements 3631 a, 3631 b, 3631 c, 3631 d used to readthe code of the detection member also serve as a field sensor forcapacity sensing. The circuitry for reading the code of the detectionmember and for capacity sensing may be shared or may be separatecircuits as previously discussed.

In this example implementation, treatment housing 3621 is anon-conductive housing containing treatment media for the filtration ofliquids or gases. The reader/capacity sensor 3620 is positioned adjacentand external to treatment housing 3621. For example, reader/capacitysensor 3620 may be configured to securely mount to the external surfaceof housing 3621. In other examples, reader/capacity sensor 3620 may bepositioned external to the treatment housing 3621 and a gap may existbetween an inner surface of the reader/capacity sensor 3620 and an outersurface of the treatment housing 3621. The reader/capacity sensor 3620may be connected to the treatment housing 3621 by a mechanicalconnection by, for example, one or more fasteners, one or more clamps,one or more ridges or grooves in the surface of the treatment housing3621 and reader/capacity sensor 3620, or the like. In the example ofFIG. 36A, reader/capacity sensor 3620 is positioned in a center of alongitudinal axis of the treatment housing 3621. In other examples, thereader/capacity sensor 3620 may be positioned near an end of thetreatment housing 3621. In other examples, the reader/capacity sensor3620 may be varyingly positioned between the end and the center of thetreatment housing 3621.

In general, reader/capacity sensor 3620 may incorporate user interfaceelements that provide visual and/or audible indications of the relatedto the code of the detection member read by the reader/capacity sensor3620 and/or the current capacity of the treatment media. In the exampleof FIGS. 36A and 36B, a test/reset button 3622 is located on an outersurface of the reader/capacity sensor 3620. In some examples, thetest/rest button 3622 may be accompanied by text indicating, forexample, “test” and/or “reset.” In some examples, the test/reset button3622 may include an indicator light such as, for example, a lightemitting diode, incandescent bulb, or the like. In some examples, thetest/reset button 3622 may be raised from the surface of thereader/capacity sensor 3620. In other examples, the test/reset button3622 may be recessed from the surface of the reader/capacity sensor3620. In some examples, the test/reset button 3622 may be configured toturn-on or turn-off a user interface 3624. In some examples, thetest/reset button 3622 may be configured to reset the reader/capacitysensor 3620 and user interface 3624.

In the example of FIGS. 36A and 36B, a user interface element 3624includes, for example, a plurality of lights such as, for example, lightemitting diodes, incandescent bulbs, or the like. In other examples,user interface 3624 may include, for example, a graphical interface, atouch screen, or the like. In some examples, the indicator lightscorrespond to the treatment media lifetime or capacity. For example,full treatment media lifetime or capacity (e.g., a new treatment media)may be indicated by illumination of all indicator lights, whereas fewerlights may be illuminated as the treatment media lifetime or capacitydecreases. In some examples, the indicator lights may be one or morecolors where designated colors and/or shading variations transition fromfull to empty capacity. In some examples, user interface 3624 may beaccompanied by text indicating, for example, “lifetime” or a series ofpercentages corresponding to the remaining treatment media lifetime orcapacity (e.g., 0%, 25%, 50%, 75%, and 100%). %). In some examples, theuser interface 3624 as a graphical interface may be represented as a piechart (e.g., circular gauge), bar chart, or the like. In other examples,the measured remaining treatment media lifetime or capacity may bedisplayed as a time interval (e.g., days) or a remaining volume of fluidthat may be treated to a predetermined purity or quality (e.g.,gallons).

Although not shown in FIGS. 36A and 36B, reader/capacity sensor 3620includes an internal antenna (not shown) arranged to form conductiveloops that encircle treatment housing 3621. An internal power source,such as a battery, and transceiver of reader/capacity sensor 3620 drivean alternating electrical current 3626 through the antenna so as toproduce magnetic field 3628. In general, magnetic field 3628 propagatesthrough at least a portion of the treatment media contained withintreatment housing 3621.

As previously described above, the treatment media within housing 3621interacts with magnetic field 3628 produced by reader/capacity sensor3620. For example, magnetic field 3628 may interact with the treatmentmedia to induce eddy currents within the treatment media. Creation ofthe field eddy currents in turn operate to reduce a strength of themagnetic field produced by the antenna of reader/capacity sensor 3620. Acontroller within reader/capacity sensor 3620 monitors characteristicsof the antenna while producing magnetic field 3628 and, based on thosecharacteristics, determines qualities (strength, amplitude, phase, etc.)of the resultant magnetic field being produced. By monitoring changes incertain qualities of the magnetic field 3628, the controller in turndetects changes in characteristics of the contained treatment media,such as changes in treatment media conductivity, dielectric constant, ormagnetic permeability over time due to filtration of particulates.

In general, treatment media may be used in a broad range of applicationsinvolving filtration, separation, and purification of fluids (liquid andgas). Example media include, although not limited to, water treatmentmedia, activated carbon, modified activated carbon, catalytic carbon,carbon, charcoal, titanium dioxide, non-wovens, electrets, air treatmentmedia, water disinfectant removal media, particulate removal media,organic content removal, ion-exchange media, reverse osmosis media, ironremoval media, semipermeable membranes, molecular sieves, sand, magnets,screens, and barrier media. Example filtration techniques with whichsensors described herein may be used include, as examples: absorption,chemisorption, physisorption, adsorption, precipitation, sublimation,ion-exchange, exclusion, extraction, electrophoresis, electrolysis,reverse osmosis, barrier membranes, sedimentation, distillation, and gasexchange. The following table illustrates example antennacharacteristics that may be influenced by treatment media propertiessuch that changes to those antenna characteristics can be detected bythe controller in accordance with reader/capacity sensors describedherein:

Change in filter media property electrical magnetic magnetic dielectricdielectric Sensor Element conductivity permeability loss tangentconstant loss tangent Inductive Element Inductance, Inductance,Resistance, L, RL, Antenna Reactance, Reactance, Q-Factor Resistance,Resistance, Q-Factor Q-Factor Capacitance Element Capacitance,Resistance, C, RC, Antenna Reactance, Q-Factor Resistance, Q-FactorResonant Circuit Inductance, Inductance, Resistance, Capacitance,Resistance, LC, LCR, Antenna, Reactance, Reactance, Q-Factor Reactance,Q-Factor Resonant Antenna Resistance, Resistance, Resistance, Q-Factor,Q-Factor, Q-Factor, Resonant Resonant Resonant Frequency FrequencyFrequency *An resoanat and non-resonant antenna may have both inductiveand capacitance elements

As one example, in activated carbon water filtration, reader/capacitysensor 3620 may be configured to detect changes to the conductivity of atreatment media over the lifetime of the treatment media. As an example,water treatment systems are often deployed for dechlorination to removepreviously added chlorine. That is, water disinfection is typicallyaccomplished by the addition of sodium hypochlorite solution (NaOCl),solid calcium hypochlorite (Ca(OCl)2), chlorine gas (Cl2), ormonochloramine (NH2Cl). Chlorine dissociates in the presence of waterfor form hypochlorite (OCl—) and hypochlorous acid (HOCl), as shown bythe following reactions:Cl2(g)+H2O(1)

HOCl+H++Cl—HOCl

H++OCl—

Water filtration systems are often deployed for subsequentdechlorination to remove the chlorine because the presence of excesschlorine in water produces an undesirable taste, odor, membranedegradation in reverse osmosis and nanofiltration systems, and the like.Flowing water through a highly porous activated carbon filter aids indechlorination by reducing chlorine to chloride through, for example,oxidation of the activated carbon treatment media. Representativechemical equations are shown below:C(s)+HOCl(aq)

CO*(s)+H++Cl—C(s)+OCl-(aq)

CO*(s)+Cl—

where CO* represent an oxidative carbon site on the activated carbontreatment media. In this way, chlorine is reduced to chloride, which issafe for human consumption, reduces undesirable taste and order, and issafe for additional water conditioning methods.

As explained herein, responsive to the dechlorination process, theelectrical conductivity of an activated carbon filter decreases overtime. As explained herein, surface oxidation over time results in asignificant decrease in the electrical conductivity of the activatedcarbon filter. Moreover, as explained herein, any change in conductivityof the treatment media in turn influences magnetic field 3628 generatedby reader/capacity sensor 3620, which is detected by reader/capacitysensor 3620. By periodically producing and sensing the resultantmagnetic field 3628, reader/capacity sensor 3620 is able to measure theconductivity decrease of the activated carbon filter duringdechlorination and, therefore, determine the percentage of the oxidizedsurface sites and the remaining lifetime or capacity of the filter. Themeasured remaining lifetime is displayed on user interface 3636, whichmay represent a percentage of the total capacity, a time interval suchas days, or a volume (measurement) of water. Alternatively,reader/capacity sensor 3620 may communicate the results to a centralmonitor for centralized reporting and alerting.

As such, in this example scenario, reader/capacity sensor 3620 maypredict and alert an upcoming chlorine breakthrough for an activatedcarbon treatment media, which is characterized as when a filtratechlorine concentration surpasses a threshold chlorine concentration. Inthis way, reader/capacity sensor 3620 may facilitate activedetermination and early notification of the chlorine breakthrough.

FIG. 36B is a schematic diagram illustrating in further detail anexample electromagnetic field created by the example indirect contactreader/capacity sensor 3620. In the example of FIG. 36B, the internalantenna (not shown) of reader/capacity sensor 3620 forms a magneticfield 3628 that travels through at least a portion of the interior spacedefined by the annular shape of the reader/capacity sensor 3620. In someexamples, a conductive material in the treatment media generates an eddycurrents (not shown) in the presence of a first magnetic field 3628. Theeddy currents in the treatment media results in the creation of a secondmagnetic field (not shown) that opposes the first magnetic field 3628.The second magnetic field in turn lowers the overall strength of themagnetic field 3628. In some examples, the magnitude of the eddycurrents and the second magnetic field depend on the electricalconductivity of the treatment media. In this way, the finite electricalconductivity of the treatment media represents an energy loss mechanismdetected by reader/capacity sensor 3620. In some examples, the energyloss mechanism may be used to determine the conductivity or conductivitychange of the treatment media by monitoring the electroniccharacteristics of the antenna such as, for example, inductance,capacitance, resonant frequency, quality factor, equivalent seriesresistance, or equivalent parallel resistance. In other examples, theantenna may be configured to be a resonant circuit. In this way, theconductivity or conductivity change of the treatment media is determinedby monitoring, for example, inductance, capacitance, resonant frequency,quality factor, equivalent series resistance, equivalent parallelresistance, or the like. For example, the resonant frequency (f_(o)) ofthe non-contact sensor can be determined from the inductance (L) and thecapacitance (C):

$f_{o} = {\frac{1}{2\pi\sqrt{LC}}.}$

The quality factor (Q) of the resonant circuit is determined by theseries reactance (X_(s)) and the series resistance (R_(s)) at resonance:

$Q = {\frac{X_{s}}{R_{s}}.}$

At resonance, the series capacitance reactance (X_(c,s)) and the seriesinductive reactance (X_(L,s)) are equal:

$X_{c,s} = \frac{1}{2\pi\; f_{o}C}$

X_(L, s) = 2π f_(o)L.

A change in inductance or capacitance will change the f_(o) of thesensor and change the parallel resistance (R_(p)) of the sensor. In thecase where the resonant frequency change is caused by a change incapacitance, the corrected parallel resistance of the sensor is given inthe equation:

$R_{p} = {R_{p,o}\left( \left( \frac{{\Delta\; f} + f_{o}}{f_{o}} \right)^{2} \right)}$

In the case where the resonant frequency change is caused by a change ininductance, the corrected parallel resistance of the sensor is given inthe equation:

$R_{p} = {{R_{p,o}\left( \left( \frac{f_{o}}{{\Delta\; f} + f_{o}} \right)^{2} \right)}.}$

In some examples, an impedance evaluation module (not shown) may be usedto monitor, for example, inductance, capacitance, resonant frequency,quality factor, equivalent series resistance, equivalent parallelresistance, or the like to determine one or more parameters of thetreatment media such as, for example, conductivity, dielectric strength,magnetic permeability, and the like. In this way, for example,monitoring the inductance, capacitance, resonant frequency, qualityfactor, equivalent series resistance, equivalent parallel resistance, orthe like, may provide real-time indication of treatment media lifetimeor capacity, which is advantageous over methods that estimate treatmentmedia lifetime or capacity based on duration of operation or total fluidvolume treated.

Reader/capacity sensor 3620 includes one or more capacity sensingelements such as, for example, an antenna, an inductor-capacitor (LC)circuit, an inductor-capacitor-resistor circuit (LCR), aninductor-resistor (LR) circuit, a capacitor-resistor (CR) circuitnear-field coupled to treatment media. Reader/capacity sensor 3620 alsoincludes sensor elements configured to read the code of a detectionmember of the treatment cartridge to detect a presence of the treatmentcartridge and/or to authenticate, identify, and/or classify thecartridge. In some example implementations, reader/capacity sensor 3620may include additional components designed to measure additional systemparameters that are used to compensate for drift and environmentalconditions that affect the properties of the capacity sensing antennaand/or field sensor. Example additional parameters that may be measuredand used to adjust capacity sensing measurements include flow rate,inlet pressure, outlet pressure, pressure drop, fluid temperature,ambient temperature, sensor temperature, electronics temperature,contaminate type sensor, and time. For example, compensation of thetemperature dependence of the parallel resistance of the antenna elementis caused by the temperature dependence of resistivity of the conductorthat comprises the antenna, as such the parallel resistance (R_(p,T)) ofthe antenna can be calculated by:

$R_{p,T} = {\frac{R_{p,o}}{\left( {1 + {\alpha\left( {T_{a} - T_{a,o}} \right)}} \right)} = \frac{R_{p,o}}{\left( {1 + {\alpha\left( {\Delta\; T_{a}} \right)}} \right)}}$

where R_(p,o) is the parallel resistance of the antenna at T=T_(o), α isthe temperature coefficient of resistivity of the antenna, T_(a) is thetemperature of the antenna, T_(a,o) is the reference temperature of theantenna, and ΔT_(a) is the change in temperature of the antenna. Whereasthe treatment media, for example, has a temperature dependenceresistivity (R_(f,T)) that can be calculated by:

$R_{f,T} = {\frac{R_{f,o}}{\left( {1 + {\beta\left( {T_{w} - T_{w,o}} \right)}} \right)} = \frac{R_{f,o}}{\left( {1 + {\beta\left( {\Delta\; T_{w}} \right)}} \right)}}$

where R_(f,o) is the resistance of the treatment media at T=T_(o,β) isthe temperature coefficient of resistivity of the treatment media, T_(w)is the temperature of the water, T_(w,o) is the reference temperature ofthe water, ΔT_(w) is the change in temperature of the water.

As such, in various examples, treatment capacity can be determinedthrough measuring conductivity of the treatment media during treatment.To determine treatment capacity, the treatment media is disposed in thenear-field of a resonant antenna. The equivalent parallel resistance ofthe resonant antenna at resonance is measured during the filtrationprocess. By measuring the equivalent parallel resistance of the resonantantenna at resonance, the coupled equivalent resistance of the treatmentmedia can be monitored. Treatment capacity can be determined based on apredetermined correlation between coupled equivalent resistance of thetreatment media and treatment capacity.

In another example, treatment media is disposed in the near-field of anon-resonant loop antenna. The equivalent series resistance of thenon-resonant loop antenna is measured during the filtration process. Bymeasuring the equivalent series resistance of the non-resonant antenna,the coupled equivalent resistance of the treatment media can bemeasured. The measured coupled equivalent resistance is used todetermine the treatment capacity based on a predetermined correlationwith the treatment capacity.

In another example, treatment media is disposed in the near-field of acapacitance element. The equivalent parallel resistance of thecapacitance element is measured during the filtration process. Bymeasuring the change in equivalent parallel resistance of a capacitanceelement, the coupled equivalent resistance of the treatment media can bemeasured. The measured equivalent resistance is used to determine thetreatment capacity based on a predetermined correlation between thecoupled equivalent resistances of the treatment media and treatmentcapacity.

The sensitivity of sensor may be defined as the sensor change caused bya unit change in the object to be sensed. For the examples describedabove, sensor sensitivity can be improved by increasing the parallelresistance of the antenna or capacitance element in the absence of thetreatment media. Construction of an antenna with a high parallelresistance in the absence of the treatment media may require high costmaterials, high cost component design/construction, and increased sensorsize. Additionally, electronics suitable to read a sensor with a highparallel resistance may require high cost electronic components andadvanced algorithms. In a practical system design, the system designermay have to consider the interdependency between sensor sensitivity andsensor cost. In one embodiment, the parallel resistance of the antennais between 100Ω and 10 kΩ. In a second embodiment, parallel resistanceof the antenna greater than the coupled resistance of the treatmentmedia. In a third embodiment, the parallel resistance of the antenna isgreater than 0.001 times the coupled resistance of the treatment.

Sensitivity may be improved by achieving a higher quality factor. Forthe same reasons described above, design of an antenna with a highquality factor may be impractical. In one embodiment, the quality-factorof the antenna is higher than 10 and lower than 1000. In a secondembodiment, the quality factor of the antenna is between 50 and 200.

In addition, increasing the operational frequency of an antenna may leadto higher sensor sensitivity. As the operational frequency for a givenantenna increases, the reactance typically has a larger increasecompared to the resistance, which leads to a higher quality factor andparallel resistance of the antenna. In some applications, increasing theoperational frequencies may be impractical as the required electronicsmay be of a higher cost, consume additional power, and exceedgovernmental emission limitations. In one embodiment, the operationalfrequency is between 1-30 MHz. In a second embodiment, the operationalfrequency resides within one or more industrial, scientific and medical(ISM) radio bands.

Sensor sensitivity can be improved by increasing the magnitude of thenear-field coupling between the antenna and the treatment media. Themagnitude of the near-field coupling coefficient can range from 1(perfect coupling) to 0 (no coupling). In practical design, realizinghigh coupling is limited by system geometrical constraints, such as theseparation of the antenna and treatment media caused by the presence ofthe treatment housing or the presence of a fluid. In one embodiment, thecoupling coefficient is higher than 0.1.

In some applications, the capacity sensor may be required to only detectwhen the treatment media capacity falls below a threshold. In thisapplication, a capacity sensor with low sensitivity may be acceptable.In some applications, the capacity sensor may be required to have a highresolution of the treatment media capacity during the entire lifetime ofthe treatment media. In this application, a capacity sensor with highsensitivity may be required.

In some implementations, treatment capacity is determined by measuringthe magnetic permeability of the treatment media during treatment. Todetermine treatment capacity, the treatment media is disposed in thenear-field of a resonant antenna. The resonant frequency of the resonantantenna is measured during the filtration process. By measuring theresonant frequency of the antenna, the magnetic permeability of thetreatment media can be monitored. The measured magnetic permeability isused to determine the treatment capacity based on a predeterminedcorrelation between magnetic permeability and treatment capacity.

In some embodiments, treatment media is disposed in the near-field of anon-resonant loop antenna. The inductance of the non-resonant loopantenna is measured during the filtration process. By measuring theinductance of the non-resonant antenna, the magnetic permeability of thetreatment media can be measured. The measured permeability is used todetermine the treatment capacity based on a predetermined correlationbetween treatment media permeability and treatment capacity.

In some embodiments, the treatment media is disposed in the near-fieldof a non-resonant loop antenna. The equivalent parallel resistance ofthe non-resonant loop antenna is measured during the filtration process.By measuring the change in equivalent parallel resistance of thenon-resonant antenna, the magnetic loss tangent of the treatment mediacan be measured. The measured loss is used to determine the treatmentcapacity based on a predetermined correlation between magnetic losstangent and treatment capacity.

In some embodiments, treatment capacity is determined by measuring thedielectric constant of the treatment media during treatment. Todetermine treatment capacity, the treatment media is disposed in thenear-field of a capacitor element. The capacitance of the capacitorelement is measured during the filtration process. By measuring thecapacitance of the capacitor element, the dielectric constant of thetreatment media can be measured. The measured dielectric constant isused to determine the treatment capacity based on a predeterminedcorrelation between dielectric constant and treatment capacity.

In some embodiments, treatment media is disposed in the near-field of acapacitor element. The equivalent parallel resistance of the capacitorelement is measured during the filtration process. By measuring thechange in equivalent parallel resistance of the capacitor element, thedielectric loss tangent of the treatment media can be measured. Themeasured loss is used to determine the treatment capacity based on apredetermined correlation between dielectric loss tangent and treatmentcapacity.

In some embodiments, chlorine from a municipal water source is treatedby a catalytic reduction process of an activated carbon filter block.During filtration, surface oxidation reduces the number of catalyticsites on the carbon block and decreases the capability of the carbonblock to filter chlorine. Oxidation of the activated carbon blockresults in a decreased electrical conductivity of the filter block.Based on this mechanism, treatment capacity may be correlated to theconductivity of the filter block.

In some embodiments, a non-conductive filter membrane is designed tofilter electrically conductive particles dispersed in a liquid. Duringfiltration, conductive particles captured by the treatment media causesthe effective resistance of the filter to decrease. As more conductiveparticles are captured by the filter, the capacity of the filter tocapture additional particles decreases. Based on this mechanism,treatment capacity may be correlated to the conductivity of the filtermembrane.

In some embodiments, a third example, iron contained within waterderived from a residential well water source is filtered with anon-magnetic filter block. During filtration, iron particles captured bythe treatment media cause the effective permeability of filter toincrease. As more iron particles are captured by the filter, thecapability of the filter decreases. Based on this mechanism, treatmentcapacity may be correlated to magnetic permeability of the filter.

In some embodiments, volatile organic content in filtered by granularcarbon attached to a personal respirator device. During filtration,adsorption of the organic content of the carbon surface causes thedielectric constant of the carbon to increase. The dielectric constantincreases because the organic content has a higher dielectric constantcompared to the displaced air. As organic content adsorbs to the surfaceand prevents additional organic contact adsorption, the filtercapability decreases. Based on this mechanism, the treatment capacitymay be correlated to the dielectric constant of the filter.

In some embodiments, air particles are treated by a non-woven electretfilter in a residential furnace. During filtration, particle loading ofthe filter causes the dielectric constant of the filter to increase. Asmore particles are captured by the filter, the treatment capability tocapture additional particles decreases. Based on this mechanism,treatment capacity may be correlated to the dielectric constant of thefilter.

FIGS. 37A-37K are block diagrams illustrating relative positions andorientations between a capacity sensing antenna 3763 and treatment media3768 in accordance with various embodiments of a reader/capacity sensor.In general, reader/capacity sensors as described herein can include anyorientation between the capacity sensing antenna 3763 and treatmentmedia 3768 capable of causing at least a portion of a generated magneticfield of antenna 3763 to interact with the treatment media 3768. When atleast a portion of the magnetic field of antenna 3763 is incident on thetreatment media 3768, the treatment media 3768 and antenna 3763 are innear-field electromagnetic interaction, also referred to herein asnear-field coupled, inductively coupled, magnetically coupled, andelectromagnetically coupled. Several example embodiments are shown inFIGS. 37A-37K. In these embodiments, antenna 2563 is depicted as theplane where an antenna resides and the antenna is positioned in avariety of orientations relative to the treatment media. Moreover, asshown in the examples, antenna 3763 may be exterior to treatment housing3764, interior to the treatment housing 3764 and proximal to thetreatment media, or disposed within portions of the treatment media.Antenna 3763 can be a conductive loop with different parameters such asnumber of turns, diameter, and conductor thickness. Although not shown,antenna 3763 may not be limited to a planar antenna but can have a thirddimension such as a coil inductor or antenna turns with different normaldirections. As previously discussed, in some of these embodiments, theantenna 3763 may also serve as a sensor element to read the detectionmember code.

Embodiments disclosed herein include:

Embodiment 1

A fluid treatment cartridge comprising:

a housing comprising a fluid inlet and a fluid outlet;

a treatment media contained within the housing; and

a detection member comprising at least one closed electricallyconductive loop comprising at least two spatially separate sections,each of the at least two spatially separate sections generating amagnetic response predetermined by the physical shape of the at leasttwo spatially separate sections when at least one section of the atleast two spatially separate sections is electromagnetically excited,the magnetic response comprising at least one of a predeterminedmagnetic phase response and a predetermined magnetic amplitude response,the predetermined magnetic response of at least one other section of theat least two spatially separate sections corresponding to at least a onedigit code.

Embodiment 2

The fluid treatment cartridge of embodiment 1, wherein a first magneticamplitude response of a first section of the at least two spatiallyseparate sections of the closed electrically conductive loop isdifferent from a second magnetic amplitude response of a second sectionof the at least two spatially separate sections of the closedelectrically conductive loop.

Embodiment 3

The fluid treatment cartridge of any of embodiments 1 through 2, whereina first magnetic phase response of a first section of the at least twospatially separate sections of the closed electrically conductive loopis different from a second magnetic phase response of a second sectionof the at least two spatially separate sections of the closedelectrically conductive loop.

Embodiment 4

The fluid treatment cartridge of any of embodiments 1 through 3, furthercomprising a cross over disposed between first and second sections ofthe at least two spatially separate sections of the closed electricallyconductive loop, the cross over changing an angular direction of currentflow through the second section relative to a direction of current flowthrough the first section.

Embodiment 5

The fluid treatment cartridge of any of embodiments 1 through 4,wherein:

the at least two spatially separate sections of the closed electricallyconductive loop comprise:

-   -   a first section having a first magnetic phase response;    -   a second section having a second magnetic phase response that is        different from the first magnetic phase response; and

a cross over between the first section and the second section, the crossover comprising:

-   -   a first loop portion;    -   a second loop portion that crosses over the first loop portion;        and    -   an electrically insulating material between the crossed over        first loop portion and second loop portion.

Embodiment 6

The fluid treatment cartridge of any of embodiments 1 through 5, whereinthe at least two spatially separate sections of the closed conductiveloop comprise:

-   -   a first section having a first non-electrically conductive area        inside the closed electrically conductive loop and a first        magnetic amplitude response; and    -   a second section having a second non-electrically conductive        area inside the closed electrically conductive loop that is        greater than the first non-electrically conductive area and a        second magnetic amplitude response that is different from the        first magnetic amplitude response.

Embodiment 7

The fluid treatment cartridge of embodiment 6, wherein the first sectioncomprises a notch in the closed electrically conductive loop, the notchextending across at least about 10% of the first section.

Embodiment 8

The fluid treatment cartridge of any of embodiments 1 through 7, whereinthe at least two spatially separate sections comprise:

a notched section containing at least one notch; and

an un-notched section, wherein a largest circle that will fit withininner edges of the shortest conductive path of the closed electricallyconductive loop in the un-notched section has diameter d1 and a largestcircle that will fit within the inner edges of the shortest conductivepath of the closed electrically conductive loop in the notched sectionhas diameter d2 and d1>d2.

Embodiment 9

The notched section of embodiment 8, wherein a largest circle that willfit within the inner edges of the closed electrically conductive loop inthe notched section has diameter d2<3 cm.

Embodiment 10

The fluid treatment cartridge of any of embodiments 1 through 9, whereinthe at least two spatially separate sections of the closed conductiveloop comprise a branched section having two or more electricallyconductive branches that are electrically connected in parallel.

Embodiment 11

The fluid treatment cartridge of any of embodiments 1 through 10,wherein at least one section of the at least two spatially separatesections of the closed electrically conductive loop includes anelectrically conductive area that supports eddy currents disposed withina shortest conductive path of the closed electrically conductive loop.

Embodiment 12

The fluid treatment cartridge of embodiment 11, wherein the electricallyconductive area is at least about 10% of a non-conductive areaencompassed within the at least one section.

Embodiment 13

The fluid treatment cartridge of any of embodiments 1 through 12,wherein the at least two spatially separate sections of the closedelectrically conductive loop comprise a first section having a firstnumber of inductive turns and a second section having a second number ofinductive turns where the first number is greater than the secondnumber.

Embodiment 14

The fluid treatment cartridge of any of embodiments 1 through 13,wherein a length of the shortest electrical path of the closedelectrically conductive loop is less than about 24 cm.

Embodiment 15

The fluid treatment cartridge of any of embodiments 1 through 14,wherein a non-conductive area encompassed within a shortest electricalpath of the closed electrically conductive loop is less than about 25cm².

Embodiment 16

The fluid treatment cartridge of any of embodiments 1 through 15,wherein the closed electrically conductive loop has an inductance lessthan about 150 nH.

Embodiment 17

The fluid treatment cartridge of any of embodiments 1, wherein theclosed electrically conductive loop is a single inductive turn loop.

Embodiment 18

The fluid treatment cartridge of any of embodiments 1 through 17,wherein the at least one closed electrically conductive loop comprisesat least three spatially separate sections, each of the three spatiallyseparate sections generating a predetermined magnetic response when atleast one section of the three spatially separate sections iselectromagnetically excited, the magnetic responses of at least twoother sections of the three spatially separate sections corresponding toat least a two digit code.

19. The fluid treatment cartridge of any of embodiments 1 through 18,wherein the at least one closed electrically conductive loop comprisestwo closed electrically conductive loops that are inductively coupled.

Embodiment 20

A system comprising:

a fluid treatment cartridge comprising:

-   -   a housing comprising a fluid inlet and a fluid outlet;    -   a treatment media contained within the housing; and    -   a detection member comprising at least one closed electrically        conductive loop comprising at least two spatially separate        sections, each of the sections generating a magnetic response        predetermined by the physical shape of the at least two        spatially separate sections when at least one section of the at        least two spatially separate sections is electromagnetically        excited, the magnetic response comprising at least one of a        predetermined magnetic phase response and a predetermined        magnetic amplitude response, the predetermined magnetic response        of at least one other section of the at least two spatially        separate sections corresponding to at least a one digit code;        and a reader comprising:    -   at least one transmit element configured to transmit an        electromagnetic signal that electromagnetically excites the at        least one section of the closed electrically conductive loop;        and    -   at least one receive element, the predetermined magnetic        response of the at least one other section of the closed        conductive loop generating a signal on the at least one receive        element that represents the code.

Embodiment 21

The system of embodiment 20, wherein the reader includes multiplespatially separated receive elements, each receive element correspondingrespectively to a section of the closed conductive loop, and signalsgenerated on the multiple receive elements represent a multi-digit code.

Embodiment 22

The system of any of embodiments 20 through 21, further comprisingreader circuitry configured to process the signal and to identify thecode.

Embodiment 23

The system of embodiment 22, wherein:

the reader circuitry is configured to detect at least one of:

-   -   a phase difference between a phase of the signal of the receive        element and a phase of the electromagnetic signal transmitted by        the transmit element; and    -   an amplitude difference between an amplitude of a first signal        of a first receive element and an amplitude of a second signal        of a second receive element or an amplitude difference between        the amplitude of the first signal and a baseline amplitude.

Embodiment 24

The system of any of embodiments 20 through 23, wherein the readercircuitry is configured to detect one or both of a presence of thefluidic treatment cartridge and a characteristic of the fluid treatmentcartridge based on the code.

Embodiment 25

A method, comprising:

electromagnetically exciting at least one section of a closedelectrically conductive loop of a fluidic treatment cartridge thatincludes a housing having a fluidic inlet, a fluidic outlet, and atreatment media disposed within the housing;

generating a predetermined magnetic response in at least another sectionof the closed electrically conductive loop in response toelectromagnetic excitement of the at least one section of the closedconductive loop, the predetermined magnetic response comprising at leastone of a magnetic phase response and a magnetic amplitude response andcorresponding to at least a one digit code.

Embodiment 26

The method of embodiment 25, wherein generating the predeterminedmagnetic response comprises at least one of:

reversing an angular direction of current flow in the closedelectrically conductive loop;

inducing a current flow through a notched section of the closedelectrically conductive loop;

dividing current flow into at least two branches of a branched sectionof the closed electrically conductive loop;

inducing a current flow through a multiple inductive turn section of theclosed electrically conductive loop; and

generating eddy currents in an electrically conductive area of a sectionof the closed electrically conductive loop.

Embodiment 27

The method of an of embodiments 25 through 26, further comprising:

fluidically coupling the fluidic inlet and fluidic outlet of the fluidictreatment cartridge to a host device;

transmitting an electromagnetic signal from a reader of a host devicethat electromagnetically excites the at least one section of the closedelectrically conductive loop;

and sensing the predetermined magnetic response in the reader of thehost device; and

generating an electrical signal that represents the code in response tothe predetermined magnetic response.

Embodiment 28

The method of embodiment 27, further comprising at least one of:

detecting a proximity of the fluidic cartridge to the host device basedon the code, the code being a one bit binary code;

detecting a characteristic of the fluidic cartridge based on the code,the code being a multi-bit binary code; and

controlling an operation of the host device based on the code.

Embodiment 29

A device comprising:

a housing comprising a fluid inlet and a fluid outlet;

a treatment media contained within the housing; and

a detection member comprising at least one closed electricallyconductive loop comprising multiple spatially separate loop sectionsincluding at least one excitation section and one or more response loopsections disposed respectively in multiple spatially separate sectionsof a detection area, each of the response loop sections generating apredetermined magnetic response when the excitation loop section iselectromagnetically excited, the magnetic response comprising at leastone of a predetermined magnetic phase response and a predeterminedmagnetic amplitude response, a spatial arrangement of the predeterminedmagnetic responses of the one or more response sections within themultiple detection area sections corresponding to a multi-digit code.

Embodiment 30

The device of embodiment 29, wherein at least a first response loopsection has a different predetermined magnetic response when compared toa predetermined magnetic response of another loop section.

Embodiment 31

A component, comprising:

a detection member comprising at least one closed electricallyconductive loop having at least two spatially separate sections; and

one or more engagement features configured to reversibly engage with ahost device, the engagement features configured to position the closedconductive loop relative to a reader of the host device such that atleast one section of the closed conductive loop is electromagneticallyexcited by a signal emitted by the reader and the reader senses apredetermined magnetic response of at least one other section of theclosed electrically conductive loop, the predetermined magnetic responseof the at least one other section of the at least two spatially separatesections corresponding to at least a one digit code.

Embodiment 32

The component of embodiment 31, wherein the predetermined magneticresponse comprises at least one of an amplitude response and a phaseresponse.

Embodiment 33

The component of any of embodiments 31 through 32, wherein the at leasta one digit code comprises a multiple digit code.

Embodiment 34

The component of any of embodiments 31 through 33, wherein the closedconductive loop is arranged in a single layer.

Embodiment 35

The component of any of embodiments 31 through 33, wherein the closedconductive loop is arranged in multiple layers.

Embodiment 36

The component of any of embodiments 31 through 35, wherein the closedconductive loop has a single inductive turn.

Embodiment 37

The component of any of embodiments 31 through 35, wherein the closedconductive loop comprises multiple inductive turns.

Embodiment 38

The component of any of embodiments 31 through 37, wherein:

the at least a one digit code comprises a multiple digit code; and

the at least one other section comprises at least two other sections, afirst magnetic response of a first section of the at least two othersections representing a first value of the multiple digit code and adifferent, second magnetic response of a second section of the at leasttwo other sections representing a different, second value of themultiple digit code.

Embodiment 39

The component of any of embodiments 31 through 38, wherein the code is abinary code.

Embodiment 40

The component of any of embodiments 31 through 38, wherein the code is anon-binary code.

Embodiment 41

A component comprising a detection member that includes at least oneclosed electrically conductive loop comprising at least two spatiallyseparate sections, each of the at least two spatially separate sectionsgenerating a magnetic response predetermined by the physical shape ofthe at least two spatially separate sections when at least one sectionof the at least two spatially separate sections is electromagneticallyexcited, the magnetic response comprising at least one of apredetermined magnetic phase response and a predetermined magneticamplitude response, the predetermined magnetic response of at least oneother section of the at least two spatially separate sectionscorresponding to at least a one digit code.

Embodiment 42

The component of embodiment 41, wherein the component includes featuresconfigured to reversibly engage with a host device.

Embodiment 43

The component of any of embodiments 41 through 42, wherein a firstmagnetic amplitude response of a first section of the at least twospatially separate sections of the closed electrically conductive loopis different from a second magnetic amplitude response of a secondsection of the at least two spatially separate sections of the closedelectrically conductive loop.

Embodiment 44

The component of any of embodiments 41 through 43, wherein a firstmagnetic phase response of a first section of the at least two spatiallyseparate sections of the closed electrically conductive loop isdifferent from a second magnetic phase response of a second section ofthe at least two spatially separate sections of the closed electricallyconductive loop.

Embodiment 45

The component of any of embodiments 41 through 44, further comprising across over disposed between first and second sections of the at leasttwo spatially separate sections of the closed electrically conductiveloop, the cross over reversing an angular direction of current flowthrough the second section relative to a direction of current flowthrough the first section.

Embodiment 46

The component of any of embodiments 41 through 45, wherein the at leasttwo spatially separate sections of the closed conductive loop comprise:

-   -   a first section having a first non-electrically conductive area        inside the closed electrically conductive loop and a first        magnetic amplitude response; and    -   a second section having a second non-electrically conductive        area inside the closed electrically conductive loop that is        greater than the first non-electrically conductive area and a        second magnetic amplitude response that is different from the        first magnetic amplitude response.

Embodiment 47

The component of any of embodiments 41 through 46, wherein the at leasttwo spatially separate sections comprise:

a notched section containing at least one notch; and

an un-notched section, wherein a largest circle that will fit withininner edges of the shortest conductive path of the closed electricallyconductive loop in the un-notched section has diameter d1 and a largestcircle that will fit within the inner edges of the shortest conductivepath of the closed electrically conductive loop in the notched sectionhas diameter d2 and d1>d2.

Embodiment 48

The component of any of embodiments 41 through 47, wherein the at leasttwo spatially separate sections of the closed conductive loop comprise abranched section having two or more electrically conductive branchesthat are electrically connected in parallel.

Embodiment 49

The component of any of embodiments 41 through 48, wherein at least onesection of the at least two spatially separate sections of the closedelectrically conductive loop includes an electrically conductive areathat supports eddy currents disposed within a shortest conductive pathof the closed electrically conductive loop.

Embodiment 50

The component of any of embodiments 41 through 49, wherein the at leasttwo spatially separate sections of the closed electrically conductiveloop comprise a first section having a first number of inductive turnsand a second section having a second number of inductive turns where thefirst number is greater than the second number.

Embodiment 51

The component of any of embodiments 41 through 50, wherein the closedelectrically conductive loop is a single inductive turn loop.

Embodiment 52

The component of any of embodiments 41 through 51, wherein the closedelectrically conductive loop comprises at least three spatially separatesections, each of the three spatially separate sections generating apredetermined magnetic response when at least one section of the threespatially separate sections is electromagnetically excited, the magneticresponses of at least two other sections of the three spatially separatesections corresponding to at least a two digit code.

Embodiment 53

The component of any of embodiments 41 through 52, wherein the at leastone closed electrically conductive loop comprises two closedelectrically conductive loops that are inductively coupled.

Embodiment 54

A system comprising:

a component comprising a detection member that includes at least oneclosed electrically conductive loop comprising at least two spatiallyseparate sections, each of the at least two spatially separate sectionsgenerating a magnetic response predetermined by the physical shape ofthe at least two spatially separate sections when at least one sectionof the at least two spatially separate sections is electromagneticallyexcited, the magnetic response comprising at least one of apredetermined magnetic phase response and a predetermined magneticamplitude response, the predetermined magnetic response of at least oneother section of the at least two spatially separate sectionscorresponding to at least a one digit code; and

a host device comprising a reader that includes an array of spaced apartsensor elements including at least one sensor element configured toelectromagnetically excite the at least one section and at least oneother sensor element configured to sense the magnetic response of the atleast one other section.

Embodiment 55

The system of embodiment 54, wherein the reader is configured todetermine a baseline signal for the at least one other sensor elementand to compare the baseline signal to a measured signal of the at leastone other sensor element, the measured signal corresponding to thepredetermined magnetic response of the at least one other loop section.

Embodiment 56

The system of any of embodiments 54 through 55, wherein the reader isconfigured to determine the code based on comparison of the measuredsignal to the baseline signal.

Embodiment 57

The system of any of embodiments 54 through 56, wherein the at least onesensor element configured to electromagnetically excite the at least onesection comprises multiple sensor elements configured toelectromagnetically activate multiple sections of the closed conductiveloop.

Embodiment 58

The system of embodiment 57, wherein the multiple sensor elementscomprise two sensor elements that emit out of phase electromagneticsignals that electromagnetically excite the at least one other section.

Embodiment 59

The system of embodiment 57, wherein the multiple sensor elementscomprise two sensor elements that emit in phase electromagnetic signalsthat electromagnetically excite the at least one other section.

Embodiment 60

The system of embodiment 57, wherein the component is a fluid treatmentassembly configured to contain a filter media.

Embodiment 61

The system of embodiment 60, wherein the reader is further configured todetect capacity of the filter media.

Embodiment 62

The system of embodiment 61, wherein the reader includes one or both ofan antenna and an additional sensor used to detect the capacity.

Embodiment 63

The system of embodiment 61, wherein the reader is configured such thatone or more of the sensor elements are used to detect the capacity.

Embodiment 64

A method, comprising:

electromagnetically exciting at least one section of a closedelectrically conductive loop disposed on or in a component;

generating a predetermined magnetic response in at least another sectionof the closed electrically conductive loop in response toelectromagnetic excitement of the at least one section of the closedconductive loop, the predetermined magnetic response comprising at leastone of a magnetic phase response and a magnetic amplitude response andcorresponding to at least a one digit code.

Embodiment 65

The method of embodiment 64, wherein generating the predeterminedmagnetic response comprises at least one of:

reversing an angular direction of current flow in the closedelectrically conductive loop;

inducing a current flow through a notched section of the closedelectrically conductive loop;

dividing current flow into at least two branches of a branched sectionof the closed electrically conductive loop;

inducing a current flow through a multiple inductive turn section of theclosed electrically conductive loop; and

generating eddy currents in an electrically conductive area of a sectionof the closed electrically conductive loop.

Embodiment 66

The method of embodiment 64, further comprising:

transmitting an electromagnetic signal from a reader of a host devicethat electromagnetically excites the at least one section of the closedelectrically conductive loop;

and sensing the predetermined magnetic response in the reader of thehost device; and

generating an electrical signal that represents the code in response tothe predetermined magnetic response.

Embodiment 67

The method of embodiment 66, further comprising at least one of:

detecting a proximity of the component to the host device based on thecode;

detecting a characteristic of the fluidic cartridge based on the code;and

controlling an operation of the host device based on the code.

Embodiment 68

An assembly comprising:

a detection member disposed within a detection area of the componentwherein:

-   -   the detection area includes at least two detection area        sections; and    -   the detection member includes at least one closed electrically        conductive loop comprising at least two spatially separate        sections, each spatially separate section disposed respectively        in one of the detection area sections, each of the at least two        spatially separate sections of the closed conductive loop        generating a magnetic response predetermined by a physical shape        of the section when at least one section of the at least two        spatially separate sections is electromagnetically excited, the        magnetic response comprising at least one of a predetermined        magnetic phase response and a predetermined magnetic amplitude        response, an arrangement of the at least two spatially separate        sections within the at least two detection area sections        corresponding to at least a one digit code.

Embodiment 69

The assembly of embodiment 68, wherein a number of the at least twodetection area sections is greater than a number of the at least twosections of the closed conductive loop.

Embodiment 70

The assembly of any of embodiments 67 through 68, further comprising areader that includes an array of spaced apart sensor elements, eachsensor element corresponding to one of the detection area sections, thearray of sensor elements including at least one sensor elementconfigured to electromagnetically excite the at least one section of theclosed conductive loop and at least one other sensor element configuredto sense the magnetic response from the at least two detection areasections.

Unless otherwise indicated, all numbers expressing feature sizes,amounts, and physical properties used in the specification and claimsare to be understood as being modified in all instances by the term“about.” Accordingly, unless indicated to the contrary, the numericalparameters set forth in the foregoing specification and attached claimsare approximations that can vary depending upon the desired propertiessought to be obtained by those skilled in the art utilizing theteachings disclosed herein. The use of numerical ranges by endpointsincludes all numbers within that range (e.g. 1 to 5 includes 1, 1.5, 2,2.75, 3, 3.80, 4, and 5) and any range within that range.

Various modifications and alterations of these embodiments will beapparent to those skilled in the art and it should be understood thatthis scope of this disclosure is not limited to the illustrativeembodiments set forth herein. For example, the reader should assume thatfeatures of one disclosed embodiment can also be applied to all otherdisclosed embodiments unless otherwise indicated.

The invention claimed is:
 1. A fluid treatment cartridge comprising: ahousing comprising a fluid inlet and a fluid outlet; a treatment mediacontained within the housing; and a detection member comprising at leastone closed electrically conductive loop comprising at least twospatially separate sections, each of the at least two spatially separatesections generating a magnetic response predetermined by the physicalshape of the at least two spatially separate sections when at least onesection of the at least two spatially separate sections iselectromagnetically excited, the magnetic response comprising at leastone of a predetermined magnetic phase response and a predeterminedmagnetic amplitude response, the predetermined magnetic response of atleast one other section of the at least two spatially separate sectionscorresponding to at least a one digit code, wherein the at least twospatially separate sections of the closed electrically conductive loopcomprise one or more of: a first configuration that includes: a firstsection having a first magnetic phase response; a second section havinga second magnetic phase response that is different from the firstmagnetic phase response; and a cross over between the first section andthe second section, the cross over comprising a first loop portion, asecond loop portion that crosses over the first loop portion, and anelectrically insulating material between the crossed over first loopportion and second loop portion; a second configuration that includes: afirst section having a first non-electrically conductive area inside theclosed electrically conductive loop and a first magnetic amplituderesponse; and a second section having a second non-electricallyconductive area inside the closed electrically conductive loop that isgreater than the first non-electrically conductive area and a secondmagnetic amplitude response that is different from the first magneticamplitude response; a third configuration that includes: a notchedsection containing at least one notch; and an un-notched section,wherein a largest circle that will fit within inner edges of theshortest conductive path of the closed electrically conductive loop inthe un-notched section has diameter d1 and a largest circle that willfit within the inner edges of the shortest conductive path of the closedelectrically conductive loop in the notched section has diameter d2 andd1>d2; a fourth configuration that includes at least one section havingan electrically conductive area that supports eddy currents disposedwithin a shortest conductive path of the closed electrically conductiveloop; and a fifth configuration that includes a first section having afirst number of inductive turns and a second section having a secondnumber of inductive turns where the first number is greater than thesecond number.
 2. The fluid treatment cartridge of claim 1, wherein afirst magnetic amplitude response of a first section of the at least twospatially separate sections of the closed electrically conductive loopis different from a second magnetic amplitude response of a secondsection of the at least two spatially separate sections of the closedelectrically conductive loop.
 3. The fluid treatment cartridge of claim1, wherein a first magnetic phase response of a first section of the atleast two spatially separate sections of the closed electricallyconductive loop is different from a second magnetic phase response of asecond section of the at least two spatially separate sections of theclosed electrically conductive loop.
 4. The fluid treatment cartridge ofclaim 1, further comprising a cross over disposed between first andsecond sections of the at least two spatially separate sections of theclosed electrically conductive loop, the cross over changing an angulardirection of current flow through the second section relative to adirection of current flow through the first section.
 5. The fluidtreatment cartridge of claim 1, wherein the at least two spatiallyseparate sections of the closed conductive loop comprise a branchedsection having two or more electrically conductive branches that areelectrically connected in parallel.
 6. The fluid treatment cartridge ofclaim 1, wherein a length of the shortest electrical path of the closedelectrically conductive loop is less than about 24 cm.
 7. The fluidtreatment cartridge of claim 1, wherein a non-conductive areaencompassed within a shortest electrical path of the closed electricallyconductive loop is less than about 25 cm².
 8. The fluid treatmentcartridge of claim 1, wherein the closed electrically conductive loophas an inductance less than about 150 nH.
 9. The fluid treatmentcartridge of claim 1, wherein the closed electrically conductive loop isa single turn inductive loop.
 10. The fluid treatment cartridge of claim1, wherein the closed electrically conductive loop comprises at leastthree spatially separate sections, each of the three spatially separatesections generating a predetermined magnetic response when at least onesection of the three spatially separate sections is electromagneticallyexcited, the magnetic responses of at least two other sections of thethree spatially separate sections corresponding to at least a two digitcode.
 11. The fluid treatment cartridge of claim 1, wherein the at leastone closed electrically conductive loop comprises two closedelectrically conductive loops that are inductively coupled.
 12. Thesystem of claim 1, wherein: the at least one other section comprisesmultiple sections; and the code is a multi-digit code.
 13. A fluidtreatment cartridge comprising: a housing comprising a fluid inlet and afluid outlet; a treatment media contained within the housing; and adetection member comprising at least one closed electrically conductiveloop comprising at least two spatially separate sections, each of the atleast two spatially separate sections generating a magnetic responsepredetermined by the physical shape of the at least two spatiallyseparate sections when at least one section of the at least twospatially separate sections is electromagnetically excited, the magneticresponse comprising at least one of a predetermined magnetic phaseresponse and a predetermined magnetic amplitude response, thepredetermined magnetic response of at least one other section of the atleast two spatially separate sections corresponding to at least a onedigit code, wherein: the at least two spatially separate sections of theclosed electrically conductive loop comprise: a first section having afirst magnetic phase response; a second section having a second magneticphase response that is different from the first magnetic phase response;and a cross over between the first section and the second section, thecross over comprising: a first loop portion; a second loop portion thatcrosses over the first loop portion; and an electrically insulatingmaterial between the crossed over first loop portion and second loopportion.
 14. A fluid treatment cartridge comprising: a housingcomprising a fluid inlet and a fluid outlet; a treatment media containedwithin the housing; and a detection member comprising at least oneclosed electrically conductive loop comprising at least two spatiallyseparate sections, each of the at least two spatially separate sectionsgenerating a magnetic response predetermined by the physical shape ofthe at least two spatially separate sections when at least one sectionof the at least two spatially separate sections is electromagneticallyexcited, the magnetic response comprising at least one of apredetermined magnetic phase response and a predetermined magneticamplitude response, the predetermined magnetic response of at least oneother section of the at least two spatially separate sectionscorresponding to at least a one digit code, wherein the at least twospatially separate sections of the closed conductive loop comprise: afirst section having a first non-electrically conductive area inside theclosed electrically conductive loop and a first magnetic amplituderesponse; and a second section having a second non-electricallyconductive area inside the closed electrically conductive loop that isgreater than the first non-electrically conductive area and a secondmagnetic amplitude response that is different from the first magneticamplitude response.
 15. The fluid treatment cartridge of claim 14,wherein the first section comprises a notch in the closed electricallyconductive loop, the notch extending across at least about 10% of thefirst section.
 16. A fluid treatment cartridge comprising: a housingcomprising a fluid inlet and a fluid outlet; a treatment media containedwithin the housing; and a detection member comprising at least oneclosed continuously electrically conductive loop comprising at least twospatially separate sections, each of the at least two spatially separatesections generating a magnetic response predetermined by the physicalshape of the at least two spatially separate sections when at least onesection of the at least two spatially separate sections iselectromagnetically excited, the magnetic response comprising at leastone of a predetermined magnetic phase response and a predeterminedmagnetic amplitude response, the predetermined magnetic response of atleast one other section of the at least two spatially separate sectionscorresponding to at least a one digit code, wherein the at least twospatially separate sections comprise: a notched section containing atleast one notch; and an un-notched section, wherein a largest circlethat will fit within inner edges of the shortest conductive path of theclosed electrically conductive loop in the un-notched section hasdiameter d1 and a largest circle that will fit within the inner edges ofthe shortest conductive path of the closed electrically conductive loopin the notched section has diameter d2 and d1>d2.
 17. The notchedsection of claim 16, wherein a largest circle that will fit within theinner edges of the closed electrically conductive loop in the notchedsection has diameter d2<3 cm.
 18. A fluid treatment cartridgecomprising: a housing comprising a fluid inlet and a fluid outlet; atreatment media contained within the housing; and a detection membercomprising at least one closed continuously electrically conductive loopcomprising at least two spatially separate sections, each of the atleast two spatially separate sections generating a magnetic responsepredetermined by the physical shape of the at least two spatiallyseparate sections when at least one section of the at least twospatially separate sections is electromagnetically excited, the magneticresponse comprising at least one of a predetermined magnetic phaseresponse and a predetermined magnetic amplitude response, thepredetermined magnetic response of at least one other section of the atleast two spatially separate sections corresponding to at least a onedigit code, wherein at least one section of the at least two spatiallyseparate sections of the closed electrically conductive loop includes anelectrically conductive area that supports eddy currents disposed withina shortest conductive path of the closed electrically conductive loop.19. The fluid treatment cartridge of claim 18, wherein the electricallyconductive area is at least about 10% of a non-conductive areaencompassed within the at least one section.
 20. A fluid treatmentcartridge comprising: a housing comprising a fluid inlet and a fluidoutlet; a treatment media contained within the housing; and a detectionmember comprising at least one closed continuously electricallyconductive loop comprising at least two spatially separate sections,each of the at least two spatially separate sections generating amagnetic response predetermined by the physical shape of the at leasttwo spatially separate sections when at least one section of the atleast two spatially separate sections is electromagnetically excited,the magnetic response comprising at least one of a predeterminedmagnetic phase response and a predetermined magnetic amplitude response,the predetermined magnetic response of at least one other section of theat least two spatially separate sections corresponding to at least a onedigit code, wherein the at least two spatially separate sections of theclosed electrically conductive loop comprise a first section having afirst number of inductive turns and a second section having a secondnumber of inductive turns where the first number is greater than thesecond number.
 21. A system comprising: a fluid treatment cartridgecomprising: a housing comprising a fluid inlet and a fluid outletconfigured to couple to a host device; a treatment media containedwithin the housing; and a detection member comprising at least oneclosed electrically conductive loop comprising at least two spatiallyseparate sections, each of the sections generating a magnetic responsepredetermined by the physical shape of the at least two spatiallyseparate sections when at least one section of the at least twospatially separate sections is electromagnetically excited, the magneticresponse comprising at least one of a predetermined magnetic phaseresponse and a predetermined magnetic amplitude response, thepredetermined magnetic response of at least one other section of the atleast two spatially separate sections corresponding to at least a onedigit code; and the host device includes a reader comprising: at leastone transmit element configured to transmit an electromagnetic signalthat electromagnetically excites the at least one section of the closedelectrically conductive loop, electromagnetic excitation of the at leastone section of the closed electrically conductive loop generating thepredetermined magnetic response of the at least one other section of theclosed conductive loop; and at least one receive element, configured tosense the predetermined magnetic response of the at least one othersection of the closed conductive loop and to generate a signal on the atleast one receive element that represents the code, wherein the readerincludes reader circuitry configured to perform at least one of:detecting a proximity of the fluid treatment cartridge to the hostdevice based on the code, the code being a one bit binary code;detecting a characteristic of the fluid treatment cartridge based on thecode, the code being a multi-digit code; and controlling an operation ofthe host device based on the code.
 22. The system of claim 21, whereinthe reader includes multiple spatially separated receive elements, eachreceive element corresponding respectively to a section of the closedconductive loop, and signals generated on the multiple receive elementsrepresent the multi-digit code.
 23. The system of claim 21, wherein thereader circuitry is configured to process the signal and to identify thecode.
 24. The system of claim 23, wherein: the reader circuitry isconfigured to detect at least one of: a phase difference between a phaseof the signal of the receive element and a phase of the electromagneticsignal transmitted by the transmit element; and an amplitude differencebetween an amplitude of a first signal of a first receive element and anamplitude of a second signal of a second receive element or an amplitudedifference between the amplitude of the first signal and a baselineamplitude.
 25. The system of claim 21, wherein the reader is configuredto detect one or both of a presence of the fluidic treatment cartridgeand the characteristic of the fluid treatment cartridge based on thecode.
 26. The system of claim 21, wherein the at least one transmitelement comprises multiple transmit elements configured toelectromagnetically excite multiple sections of the closed electricallyconductive loop.
 27. The system of claim 26, wherein the multipletransmit elements transmit electromagnetic signals that are out of phasewith each other.
 28. A method, comprising: fluidically coupling afluidic inlet and a fluidic outlet of a fluidic treatment cartridge to ahost device, the fluidic treatment cartridge having a housing thatincludes the fluidic inlet, the fluidic outlet, and a treatment mediadisposed within the housing; transmitting an electromagnetic signal froma reader of a host device, the electromagnetic signalelectromagnetically exciting at least one section of a closedelectrically conductive loop of a fluidic treatment cartridge;generating a predetermined magnetic response in at least another sectionof the closed electrically conductive loop in response toelectromagnetic excitement of the at least one section of the closedconductive loop, the predetermined magnetic response comprising at leastone of a magnetic phase response and a magnetic amplitude response andcorresponding to at least a one digit code; sensing the predeterminedmagnetic response in the reader of the host device; generating anelectrical signal that represents the code based on the predeterminedmagnetic response; the method further comprising at least one of:detecting a proximity of the fluidic cartridge to the host device basedon the code, the code being a one bit binary code; detecting acharacteristic of the fluidic cartridge based on the code, the codebeing a multi-bit binary code; and controlling an operation of the hostdevice based on the code.
 29. The method of claim 28, wherein generatingthe predetermined magnetic response comprises at least one of: reversingan angular direction of current flow in the closed electricallyconductive loop; inducing a current flow through a notched section ofthe closed electrically conductive loop; dividing current flow into atleast two branches of a branched section of the closed electricallyconductive loop; inducing a current flow through a multiple inductiveturn section of the closed electrically conductive loop; and generatingeddy currents in an electrically conductive area of a section of theclosed electrically conductive loop.
 30. The method of claim 28, whereingenerating the electrical signal that represents the code comprises atleast one of: determining a phase difference between a phase of a signalgenerated by a receive element of the reader in response to thepredetermined magnetic response and a phase of the electromagneticsignal transmitted by the reader; determining an amplitude differencebetween an amplitude of a first signal of a first receive element of thereader and an amplitude of a second signal of a second receive elementof the reader, the first signal generated in response to a firstpredetermined magnetic response of a first section of the closedconductive loop and the second signal generated in response to a secondpredetermined magnetic response of a second section of the closedconductive loop; and determining an amplitude difference between anamplitude of a signal generated by a receive element of the reader inresponse to the predetermined magnetic response and a baselineamplitude.